Least-squares complex frequency-domain (LSCF) method developed to be implemented in modal parameter estimation recent years. An expect result was received either in the system of weak damping or heavy damping. An User Interface was designed based on Matlab consisting of the LSCF method. Different parameters were set based on different coefficient matrixes and solution modification of the pole of the system was given. A test was used to validate the consistency of the different coefficient matrixes and that the User Interface was correct.