Abstract: Based on the contrast between afforestation seedling growth and shrub community characteristics in arid valleys of closed forest area and the non-closed forest area,researches were conducted on the effect of closing forest on arid vegetation restoration. The results showed that on the same slope and elevation gradient,the afforestation seedlings survival rate and average tree growth in closed forest area were significantly higher than those in non-closed forest area,the difference between the change extent was respectively 21% (North SlopeⅠ)~31% (North Slope Ⅲ) and 42.7% (South SlopeⅠ) to 59.7% (South SlopeⅡ); the shrub coverage and height in the closed forest area were higher than those in non closed forest forest. The difference between average coverage range of shrub and herb was 1.1% (South SlopeⅠ)~26.7% (South SlopeⅡ) and 2.2% (South SlopeⅠ)~18.5% (South SlopeⅡ) between shrubs and herb;the difference of average height was between 8.2% ((South SlopeⅠ)~53.5% (North Slope Ⅲ)) and 17.9% (North Slope Ⅲ)~28.9% (North SlopeⅡ).