Micro pulse lidar(MPL) is an effective tool for atmospheric aerosol and cloud detecting. In order to make the structure of the micro pulse lidar more compact, solve the problem that it always very difficult to adjust the transmitting and receiving optical paths to parallel in the traditional system, avoid the influence of the geometric overlap factor and reduce the complexity of the data processing, Anhui institute of optics and fine mechanics of the Chinese academy of sciences designs a new type of micro pulse lidar, particularly designs the followed up optical unit of the micro pulse lidar. A combination of emitting and receiving fibers in a signal bundle changes the structure of the subsequent optical unit in the traditional system to make the transmitting and receiving optical paths coaxial. The public end of the Y type optical fiber bundle is composed of a transmitting optical fiber in the center and eight receiving optical fibers in the periphery. After a brief introduction of the new system, the key parameters of the new micro pulse lidar system and the Y type optical fiber bundle were described in some detail. In order to verify the feasibility of the new structure of the micro pulse lidar system, a continuous observation experiment was carried out in Hefei area to detect the horizontal distribution of the atmospheric aerosol and pollutions. The data measured in the experiment in the November 2013 was processed with Fernald method and the profile of the atmospheric aerosol horizontal extinction coefficient distribution was inverted. The data inversion results showed that: the data acquired by the new lidar system and the extinction coefficient distribution inverted by Fernald algorithm are all very reasonable, and the time-space distribution of atmospheric aerosols extinction coefficient can reflect the distribution of the atmospheric aerosol and pollutions near the ground effectively. All of the experiment results indicate that the design of the new micro pulse lidar system is effective.