Abstract: Technological innovation of agricultural machinery manufacturers cannot be separated from the contribution of suppliers. Based on the cognitive evaluation theory, the relationship between different forms of supplier development and its synergy and supplier innovation contribution in agricultural machinery manufacturing enterprises was explored. SPSS software was used for hierarchical regression analysis to test the hypothesis. The empirical study from 170 manufacturers shows that different forms of supplier development have different impacts on supplier innovation contribution, incentive and direct involvement positively affects supplier innovation contribution, and competitive pressure negatively affects supplier innovation contribution. In addition, the synergy of incentive and direct involvement is more conducive to the improvement of supplier innovation contribution, while the synergy of competitive pressure and direct involvement is not conducive to the improvement of supplier innovation contribution, and the synergy of incentive and competitive pressure has no significant impact on supplier innovation contribution. The research results have some practical reference value for improving the technological innovation performance of agricultural machinery manufacturers in China.