When the dual polarization radar detects the small spheroids,it transmits single polarized waves and receives the horizontal and vertical polarization.If the rotary axes of the particles are assumed in a certain orientation,the radar meteorological equations of Z_vh and Z_hv must be established firstly,and these corresponding radar reflectivity factors are redefined.This paper derives the equations of Z_vh,Z_hv and R_{LD_vh} or R_{LD_hv}.The changes of LDR are simulated when the small spheroids have the size distribution of Gamma and their rotary axes are uniformly oriented in space.