Output performance and durability are two key issues for the practical application of triboelectric nanogenerators (TENGs). Although the soft contact structure design is a preferred strategy currently for improving the working life of TENGs, it is difficult to achieve a high output performance. Exploring physical and chemical properties of soft contact materials is a reliable way to achieve ultra-durable and high-output TENGs. Herein, an advanced structure for soft-soft contact is designed by combining ultra-soft PU foam and a spring steel sheet. The soft-soft contact triboelectric nanogenerator (SS-TENG) maintains 100% of the initial output after 1,000,000 operation cycles. More importantly, the high leakage characteristics of PU foam enable the triboelectric charge to migrate up and down inside the dielectric material, significantly improving the output performance of the SS-TENG (charge density and peak power are 144 μC/m-2 and 178   mW, respectively). This study provided an effective approach for promoting the output and durability of TENGs. Meanwhile, this work offers a reliable solution for the development of self-powered sensor networks for smart agriculture.