Farmland WSN (wireless sensor network) is characterized by numerous nodes and large area. In order to solve the problem of poor scalability and unbalanced energy consumption of farmland WSN, we proposed a mobile sink moving strategy and nodes routing strategy for Farmland WSN. By partitioning variable regions and forming restricted hops routing trees, nodes can select the optimal routing path. At the same time weighted energy center algorithm is used to select rendezvous points for the sink node which collect information by accessing each rendezvous points one by one. The algorithm reduces the complexity of path computation on the basis of prolonging the network lifetime by 5.20% and improving the node energy utilization rate.