Aiming at the problem of animal invasion in largescale farmland, an intrusion sensing system design based on NBIOT is proposed.In the experiment, the integrated sensor nodes were arranged in the test area by the new Gaussian distribution method, and compared with the nodes in the traditional uniform distribution method.At the same time, matlab simulation and field experiment were also used to summarize the optimal number of sensor nodes and the optimal sensor monitoring range of 30 and 22 m, respectively.Then, the reliability of the whole system is further determined through the calculation and analysis of the fluctuation quantity through the relevant data obtained.Through the experiment and simulation, it can be known that the sensor system can successfully and timely identify the intruder when it enters, and make timely response.The whole system can monitor the whole area in real time to prevent the intrusion.