In the field of laser circumferential detection and laser imaging, there is demand for a simple and small system. A new kind of small linear laser circumferential laser radar using a single detector is proposed. The effects of surface characteristics of two typical targets (a plane and a cylinder) on echo waves of a linear laser are investigated via modeling, theoretical analysis, and an experiment. The results show that the echo waveform is affected by the detection range, target surface condition, and target size. The rising edge, broadening, and arrival time of the echo are affected by the shape of the target. Furthermore, a simple imaging method is proposed in the last part of our study using this circumferential system based on the echo characteristic studied.