A new dual-wavelength Mie lidar(DWL) was developed for measuring the optical properties and their spatial and temporal variations of tropospheric aerosol at 532 nm and 1064 nm wavelength. Four channels are adopted to receive the far and near range backscatte■ing signals at 532 nm and 1064 nm wavelength respectively. In order to enhance the capability of daytime measurement, the system employs a narrow band interference filter to separate the main backscattering signal of lidar return, including Mie backscattering signal and Rayleigh backscattering signal from all the backscattering signals including non-elastic scattering signal and solar spectrum, by using an iris to block the majority of sky background. Overall structure and specifications of the lidar are described. Lidar data processing method is also presented. The lidar system was operated at Hefei(N31°54′, E117°10′). The profile of extinction coefficient of tropospheric aerosol and its temporal-spatial distribution were obtained. Optical depth and Angstrom exponent of aerosol are also discussed. The observed results show that this lidar works well day and night, and it has ability to measure the tropospheric aerosols and to manifest the temporal and spatial distributions of the aerosols with high precision.