A new simulation model coupling single cardiac myocyte mechanics with cardiovascular system is proposed to compute cardiovascular haemodynamics. Electrophysiology of a cardiac cell is numerically approximated by the previous model of human ventricular myocyte. Negroni and Lascano model (NL model) (Negroni & Lascano, 1996) is employed to compute the tension of single cardiac myocyte closely related to ion dynamics in cytoplasm. To convert the tension of single cell to the contractile force of ventricle, we assumed the shape of ventricle as a thin-walled hemispheric shape. A lumped parameter model with seven compartments (Heldt et al. 2002) is utilized to compute systemic circulation interacting with single cardiac cell mechanics via NL model and Laplace law. Numerical simulation shows that the typical characteristics of heart mechanics, such as pressure volume relation, stroke volume and ejection fraction, are successfully reproduced by the proposed multi-scale cardiovascular model covering from single cardiac cell to circulation system. This approach shows that the model of single cardiac myocyte can be integrated to the cardiovascular system by simple approximation.