OBJECTIVE： To optimize the formulation optimization of Nicorandil sustained-release matrix tablet， and evaluate its drug release properties in vitro. METHODS： Based on single factor test， powder direct compression method was used， using nicorandil cumulative release rate （Q） in 1， 4， 8， 12 h as evaluation indexes， central composite design-response surface method was adopted to optimize the amount of hydroxypropyl methylcellulose （HPMC） and ethyl cellulose （EC）； Q values within 12 h in different pH （1.0， 5.0， 6.8， 7.4） media were compared. RESULTS： The optimized formulation （every tablet） was nicorandil 10 mg， HPMC 150 mg， EC 90 mg， microcrystalline cellulose 80 mg， lactose 60 mg， magnesium stearate 2％. Q1 h， Q4 h， Q8 h and Q12 h of the obtained formulation were 23.6％， 51.3％， 83.7％ and 96.9％， respectively； deviation from the predicted values were 2.1％， 1.6％， 1.0％， 0.2％. Q values were similar in pH 1.0-7.4 at different time points. CONCLUSIONS： The obtained Nicorandil sustained-release matrix tablet by optimal formulation shows sustained-release effect， and the change of pH 1.0-7.4 has no interference in the release characteristics of main drug.