This paper uses constant market share model(CMS model) to analyze agricultural product export in BRICS countries.The result shows that structural effect is the main influencing factor for agricultural product export growth,among which growth effect and market effect have important influence on structural effect.The world market demand on capital-intensive agricultural product exports is weakening while that on labor-intensive agricultural product exports is growing.Capital-intensive and labor-intensive agricultural product exports in BRICS countries mainly concentrate on the market with slower demand growth..The influence of the competitive effect on agricultural product export in BRICS countries is fluctuating and agricultural trade of BRICS countries resistant to exterior competitiveness is weaker.On the whole,the competitiveness of labor-intensive agricultural product is declining while capital-intensive agricultural product is increasing.Therefore,this paper finally proposes several suggestions that BRICS countries should adjust the export growth mode and market structure,foster capital-intensive agricultural product competitiveness and strengthen exchanges and cooperation among each other.