Computer simulation study of the electrical activity of the heart is one of the frontier subjects of electrocardiogram (ECG) theory study. A new algorithm for simulating excitation propagation within the heart is presented in this paper. On the basis of this, computer simulation of QRST-wave is completed on an IBM PC microcomputer. All performance of the model is compared favourably with that of the models implemented on main frames or on high-performance work stations abroad.