Objective： To observe the effect of anti-hypertensive factor（AFBC） in bovine colostrum on the intracellular free calcium concentration （[Ca2+]i） induced by potassium chloride in adult rat cardiomyocytes， the possible mechanism of inhibiting myocardial contraction in rats was investigated. Methods： Using fluorescent properties Fura-2/AM at freshly isolated rat ventricular myocytes. Results： 0.5 mg/mL AFBC had no significant effect on resting myocardisl cells [Ca2+]i， but could depress the increase of ventricular myocytes [Ca2+]i induced by 50 mmol/L KCl. Conclusion： AFBC can block the voltage-dependent calcium channel of ventricular myocytes in adult rat.