可以参考一个解决方案: https://github.com/shitao1988/baidu/

1. 首先在页面上引入jquery、OpenLayers和百度云地图Js库；

   <script type="text/javascript" src="./js/base/jQuery.js"></script>
   <script type="text/javascript" src="./js/openlayer/OpenLayers.js"></script>
   <script type="text/javascript" src="http://api.map.baidu.com/api?v=1.3"></script>
   

2. 一张Html页面准备好map容器、准备好省、市两级下拉联动条；

3. 创建地图：

   var mapOptions = {   
        displayProjection : WGS84,  
        units: "degrees",  
        numZoomLevels:15,  
        allOverlays: true,  
        controls: [],  
        projection: WGS84,  
    maxExtent: new OpenLayers.Bounds(-180.0,-90.20209041233414,180.4041808246683,90.0),  
        };  
   map = new OpenLayers.Map('map', mapOptions);
   

4. 叠加

   var triangleCoords = [];    
   /** 
    * 根据城市名描画边界范围 
    * @author:wangyq 
    * @parameters:name，区划名，比如广东省或者东莞市 
   */  
   function makeBoundsByRegion(name){  
   //下面这句是调用百度API  
   var bdary = new BMap.Boundary();   
   var polygonArray = [];  
   triangleCoords.length=0;  
   bdary.get(name, function(rs) {  
        points = rs; //获取行政区域    
        var rslength = rs.boundaries.length;     
        var components = new Array();  
        var polygon = null;  
        for (i = 0; i < rslength; i++) {    
            var temp = rs.boundaries[i];    
            //一个temp代表一个polygon，部分区域譬如广东省边界范围中包含多个polygon，需要递归画出来  
            var latLngs = temp.split(";");    
            triangleCoords.length = 0;  
            for (j = 1; j < latLngs.length - 1; j++) {   
                var postion = latLngs[j].indexOf(",");    
                var lng = parseFloat(latLngs[j].substr(0, postion));//经度    
                var lat = parseFloat(latLngs[j].substr(postion + 1));//纬度    
                triangleCoords.push(new OpenLayers.Geometry.Point(lng,lat));    
            }  
            var k = triangleCoords.length;  
            var line = new OpenLayers.Geometry.LinearRing(triangleCoords);  
            polygon = new OpenLayers.Geometry.Polygon([line]);  
            polygonArray.push(polygon);  
        }  
        var MultiPolygon = new OpenLayers.Geometry.MultiPolygon(polygonArray);  
        var polygonBounds = new OpenLayers.Feature.Vector(MultiPolygon);  
        //设置layersname为行政边界的图层的样式  
        if(map.getLayersByName("行政边界").length==0){  
            var sketchStyle = new OpenLayers.Style(null, {  
                rules: [  
                        new OpenLayers.Rule({  
                            symbolizer: {  
                                "Polygon": {  
                                    strokeWidth: 3.5,  
                                    strokeOpacity: 1,  
                                    strokeColor: "#FF3366",  
                                    fillColor: "#ff0000",  
                                    fillOpacity: 0  
                                }  
                            }  
                        })  
                        ]  
            });  
            var myStyle = new OpenLayers.StyleMap({   
                "default":sketchStyle  
            });  
            var bouderLayer = new OpenLayers.Layer.Vector("行政边界",{  
                styleMap: myStyle,  
                projection:WGS84  
            });  
            bouderLayer.addFeatures(polygonBounds);  
            map.addLayer(bouderLayer);  
   
        }else{  
            map.getLayersByName("行政边界")[0].removeAllFeatures();  
            map.getLayersByName("行政边界")[0].addFeatures(polygonBounds);  
        }  
        var centroid = new OpenLayers.LonLat.fromString(MultiPolygon.getCentroid().x+","+MultiPolygon.getCentroid().y);  
        map.moveTo(centroid);  
   });  
   }