ABCD matrix mechanism is used to analyze and design laser resonators. In order to obtain a general method for programming, all elements of the matrix are considered as complex. Meantime, the beam quality factor M2 and the index of media are also considered. Based on Visual Basic programme language, a resonator software is developed. It can be used to analyze and design stable standing cavity, stable travelling cavity, unstable standing cavity, unstable travelling cavity, phase conjugate cavity and beam transmission and so on. One can add or delete optical elements at will. In addition to one general complex element, eighteen elements can be combined for resonators and beam trasformation. When tilted elements are inserted into optical path, the beam parameters of three planes such as ideal, tangential and sagittal are provided for comparison. Tolerance of thermal lens and optical length etc. can be optimized by dragging the button in the software easily. Cavity parameters such as stability condition, beam waist radius, beam waist position, beam radius at any position can displayed or output in certain file formats.