311-A optimum regression design was used to study effects of application of nitrogen,phosphorus and potassium on tea breeding in greenhouse in winter.The regression models was established to obtain the optimum application of NPK fertilizers.When the amount of fertilizers was N= 185.65 kg/hm2,P2O5=239.75 kg/hm2,K2O=0.00 kg/hm2,the maximum length of tea seedlings was predicted to increase 8.3 cm.