In order to extend the receiving range of scattering angles and improve the measurement accuracy and resolution of submicron particles by laser particle size analyzers, a simple-structure method based on an annular sample cell is proposed. In theory, it can receive the scattering light of 0°~180° continuously and seamlessly and possesses the advantage of low measurement limit. Based on the measurement method with annular sample cells, a new-type measurement device of laser particle sizes is constructed and the standard particles of 50, 100, 200, 400 nm and their mixtures are measured, whose results are compared with those of the traditional sample cells. The results show that the method based on the annular sample cells can distinguish the mixed standard particles with a median volume diameter ratio of 1∶2. This scheme has signatures of low measurement limit, high measurement accuracy, high resolution and high reliability for submicron particles.