A novel laser ranging method is proposed. This method avoids the processes of timing the pulse intervals or comparing the phase differences, which are done by using complex electric devices in traditional laser ranging methods. In the proposed method, the required range information is analyzed and abstracted mainly by optical ways, and is obtained by comparison of a large number of photons ultimately. Based on birefringence and total internal double reflection effects in single axis crystal, a single block LiNbO3 crystal with special structure is designed as the key device in the proposed method. The results show that this method not only simplifies the structure of devices, but also has a high precision, comparing with the traditional laser ranging methods. So a new thicking way for the laser ranging is provided.