A software package for the calculation of microstrip antenna with finite base plate is developed. The microtrip antenna is partitioned into triangle and tetrahedron using moment method. The impedance matrix is divided into four types：conductor-to-conductor，conductor-to-medium，medium-to-conductor and medium-to-medium. By calculating the four types of impedance matrix，the current coefficient is obtained and the performance of the antenna is analyzed. Finally，the software package is implemented based on matrix laboratory（MATLAB） programming environment. Compared with the simulation results of FEKO software，the software package has the advantages of simple operation，high visibility and high calculation accuracy. It can be used for the analysis and calculation of microstrip antenna with finite base plate.