Based on the data of “100 Villages, 1000 Households” of Liaoning province in 2015, the effect of joining cooperative on the adoption of new agricultural technology has been analyzed through using Probit model. The study shows that compared with non-member farmers of cooperative, member farmers are more likely to adopt new agricultural technology. Joining cooperative could significantly promote the adoption of new agricultural technology, especially for the farmers of large-scale planting and diversified planting. Farmers who join the cooperative have a higher tendency to use new agricultural technologies of seeds, fertilizer, pesticide, agricultural machinery facilities, farming methods, field management, storage and processing, irrigation, and pollution-free production. Joining cooperative has the greatest impact on pollution-free production technology and the smallest influence on pesticide technology. Further research finds that joining cooperative helps to improve technology accessibility and bargaining power, and thereby promote farmers’ adoption of new agricultural technologies.