A new kind of three-dimensional imaging laser radar is used to detect vehicle targets on the ground.Parallel linear array photodiode receiver is adopted by the laser radar to increase imaging speed.Two linear array detection modes are summarized.Their difference is the laser irradiation modes on the target;one is multi-beam laser transmitting mode,the other is floodlight laser transmitting mode.Mechanisms,implementation methods,advantages and disadvantages of the two detection modes are analyzed,and laser radar detection equations of the two detection modes are established.Signal-to-noise ratio (SNR) and ranging accuracy are adopted to analyze the detection and ranging performance of the two modes.Expressions of SNR versus range,laser transmitting power versus range are deduced,and simulation is done.Simulation results show that,under the same condition of the range and laser transmitting power,SNR of multi-beam laser transmitting mode is higher;and under the same condition of the range and ranging accuracy,the transmitting power of floodlight laser transmitting mode is higher.