Aiming at the issues of excessive authorization and difficulty handling specific large-scale access when isolating IoT large-scale access data by the “minimum privilege” principle, a secure-gateway-based isolation method is proposed. It combines similarity measurement functions for data sensitivity classification, adopts a dynamic shuttle mode to set up isolation channels as needed according to numerical attribute statistics at different levels, and adjusts isolation strategies and strength automatically. Experiments show that after classification, most data points are ideal, isolation strategy switching delays for specific and large-scale requests are low, and there’s no excessive authorization during upgrades. The method effectively enhances IoT large-scale access data isolation.