I used Google Maps to set the location of the center point of the map, why didn"t it work?

function LocalMapType() {
}
LocalMapType.prototype.tileSize = new google.maps.Size(256, 256);
LocalMapType.prototype.maxZoom = maxZoom; //
LocalMapType.prototype.minZoom = minZoom; //
LocalMapType.prototype.name = "";
LocalMapType.prototype.alt = "";
LocalMapType.prototype.getTile = function(coord, zoom, ownerDocument) {
    var img = ownerDocument.createElement("img");
    img.style.width = this.tileSize.width + "px";
    img.style.height = this.tileSize.height + "px";
    var strURL = outputPath; //
    strURL += zoom + "/" + coord.x + "/" + coord.y + format;

    img.src = strURL;
    return img;
};

var localMapType = new LocalMapType();

/*
 *
 */
function initialize() {
    var mapOptions = {
        center:new google.maps.LatLng(40.323938,116.637811),//39.921469,116.443108//x:,y:39.9224760034337, 116.394653320313),//new google.maps.LatLng(39.9224760034337, 116.394653320313),
        zoom : 11,
        streetViewControl : false,
        mapTypeControlOptions : {
            mapTypeIds : ["google_online_map"]// localMap
        }
    };

    map = new google.maps.Map(document.getElementById("map_canvas"),mapOptions);//, mapOptions

    map.mapTypes.set("google_online_map", localMapType); //
    map.setMapTypeId("google_online_map");
}

but the value of center in the map I console is the same as what I set, but after the page is displayed, it is not the central point I set. I just tried it, if it is only right during initialization, but because I have added some markers in this area, I can"t get out of the central point. Does the landmark on this map affect the central point?.