Advantages of the z-buffer method:             

1) The z-buffer method or algorithm is easy to apply and it needs no sorting of surface in a scene.

2) In z-buffer algorithm or method, an arbitrary number of objects can be handled since each object is processed at one time only. The number of objects is restricted only by the computer's memory to save the objects.

3) Easily hardware implementation.                

4) Online algorithm which we do not require to load all polygons at once in order to run algorithm.