A new high-accuracy laser ranging technology based on several photons was mentioned and verified, according to traditional linear detection needing high laser energy and photon counting detection hard to distinguish the avalanche events generated by signal or noise. Silicon Photomultiplier was used as echo detector, making analysis of the echo response model, noise characteristics and ranging accuracy. Laser ranging system was set up to measure target of the 107.86 m at laser wavelength of 532 nm and energy of 10 nJ. Experimental verification result indicates that the noise is a random distribution, which maximum magnitude equals to three pixels fired at the same time. When threshold is set above that, noise and signal can be clearly distinguished. For echo signal containing 32 photons, about four pixels are fired. Meanwhile, ranging accuracy of the system is up to 3 cm at 3 sigma.