A SRAM cell and a forming method thereof are provided. The SRAM cell includes: a pull-up transistor, a pull-down transistor, a pass gate transistor, a tensile stress film which covers the pull-up transistor and the pull-down transistor, and an interlayer dielectric isolating layer which covers the tensile stress film and the pass gate transistor. The method includes: providing a semiconductor substrate; forming a pull-up transistor, a pull-down transistor and a pass gate transistor on the semiconductor substrate; forming a tensile stress film covering the pull-up and pull-down transistors; and forming an interlayer dielectric isolating layer covering the tensile stress film and the pass gate transistor. Write margin of the SRAM cell may be increased and an area of the SRAM cell may be reduced.