During last 16 years we have successfully developed the computer-assisted vectorcardiogram analysis systems: model TJ-I, TJ-II, and TJ-III, but some technical problems remained unresolved, such as the recognition accuracy for vectorcardiograms, measurement of the parameters of complicated QRS waves, the ratio of T loop length to width, and the area of spatial vectors etc. A new system, model TJ-IV was designed to resolve these technical problems. The system was equipped with a 586 computer with a CPU of 120 MHz. Special new low-noise amplifier was employed and C language was used for programming. Three graph recognition techniques were used to enhance the accuracy of VCG recognition. 32 orthogonal electrocardiograms and vectorcardiograms were displayed and printed, and 566 parameters of vectorcardiograms were calculated. Our results with 150 cases showed that the system had high accuracy of graph recognition, and parameter calculation and the results were essentially consistent with those of manipulative methods. We were led to concluded when compared with TJ-III system, the new version has higher accuracy of processing and measurement for vectorcardiograms, is able to process more vectorcardiographic parameters, with higher processing speed.