A 3D depth imaging method and system are disclosed. The 3D depth imaging method involves radiating light at a measurement target object using a projection means and imaging the light using an image receiving means, and includes the steps of assigning a unique transmitting side address to a signal corresponding to each pixel of the projection means to encode the signal; projecting multiple light patterns at the projection means to transmit the signal; receiving the encoded signal at the image receiving means; separating the received signal to restore the address; and determining a pixel position of the object using the transmitting side address and the restored address. With the 3D depth imaging method and system, it is possible to exactly separate signals received by the image receiving means even when the signals are overlap and the geometrical structure of the object varies, and it is also possible to obtain a depth image that is robust against ambient environmental noise.