Boundary-spanning search for knowledge is an effective way for enterprises to acquire heterogeneous knowledge, and is also an important pre-stage to realize effective knowledge reconstruction. Based on the boundary-spanning search for knowledge theory, this paper studies the relationship between boundary-spanning search for knowledge and the sustainable innovation ability of agricultural enterprises considering the influence of organizational knowledge reconstruction, from a Chinese perspective. A questionnaire survey on agricultural enterprises mainly from Southeast China is conducted, and the hierarchical regression analysis method is utilized to verify five research hypotheses. The results mainly show that (1) boundary-spanning search for technology knowledge (BSSTK) and boundary-spanning search for market knowledge (BSSMK) both have a significant positive impact on the sustainable innovation ability of an agricultural enterprise; (2) organizational knowledge reconstruction plays a partial intermediary role between boundary-spanning search for knowledge (including BSSTK and BSSMK) and the sustainable innovation ability of an agricultural enterprise. From the perspective of boundary-spanning search for knowledge, this paper provides theoretical support for the promotion of sustainable innovation of an agricultural enterprise, which contributes to improving the economic sustainability of agriculture to some extent.