Phenophases of 18 cultivars of herbaceous peony (Paeonia lactiflora Pall.) introduced in Beijing were observed from 2012 to 2014, correlation degree between blooming stage and other six phenophases was analyzed by grey correlation analysis, hereby, its prediction model of blooming stage was established by multiple linear regression analysis method. The results show that correlation degree of blooming stage (Y) with bud color-changing stage (X1 ), bud showing stage (X2 ) and germination stage (X3 ) is higher, and multiple linear regression prediction model is Y =3. 516+0. 680X1 +0. 165X2 +0. 250X3 (R2 =0. 951). The prediction model is tested and its score is 333. 34 with a full mark rate of 83. 34%, indicating the prediction result of this model is better.