In today's agricultural information age, knowledge services for farmers cannot be provided without the Internet, and with the expansion of information data on the Internet, the field of agricultural planting technology has also generated a huge amount of digital information resources, among which professional knowledge presents redundancy, sparseness and diversity, requiring new means and methods to collect and store these big data and knowledge as well as to conduct knowledge Q&A in a timely manner. The aim of this paper is to study a question and answer system for agricultural cultivation technology based on knowledge graphs. Firstly, the knowledge graph model of agricultural cultivation technology is designed, and the existing deep text matching algorithm DSSM algorithm is selected. Based on the DSSM algorithm, a Bert+DSSM algorithm is proposed to improve the performance of the algorithm. The text matching algorithm, question and answer corpus and crop planting knowledge map are applied to the system to build an agricultural planting technology question and answer system, and the experimental results show that the relevant knowledge question and answer function of the system has a high accuracy rate.