The invention provides a method and a device for positioning targets. The method includes acquiring mileage data information and ambient environment information of the targets; establishing first score functions related to first location information of the targets according to laser data information and vision depth data information; carrying out gradient optimization processing on the first score functions on the basis of the mileage data information of the targets and determining the first location information of the targets. The ambient environment information at least includes the laser data information and the vision depth data information. The method and the device have the advantages that the laser data information and the vision depth data information are fused with each other, accordingly, the determined first location information of the targets is high in accuracy, and the accuracy of maps in the targets further can be improved.