A new smart U-shaped triboelectric nanogenerator (TENG) was reported basing on solid-liquid contact triboelectrification and the Pascal's law, in which the complicated mechanical motions can be transmitted into liquid pressure and electricity signal. The U-shaped TENG driven by inertial force and air flow is designed as an energy harvesting device to collect the mechanical energy with a stable peak output voltage and current of about 20 V and 400 nA, respectively. The relationship between the output performance and the water sliding conditions is investigated in detail with a stable peak output performance at the point of resonance. The U-shaped TENG can also be working as smart multifunctional sensors to detect the displacement, pressure, torsion, and so on. As a self-powered displacement sensor, the U-shaped TENG shows a high sensitivity of 0.91 V mm⁻¹ and 8.50 nA mm⁻¹. As a pressure sensor, it also exhibits a high sensitivity of 4.41 V kPa⁻¹ and 72.94 nA kPa⁻¹, respectively. This work expands the practical applications of the solid-liquid triboelectrification based TENGs for energy harvesting and smart sensors in wide fields with advantages of simple fabrication, low cost, portable and self-powered properties.