Abstract: The disclosure discloses a Fabry-Perot (F-P) cavity, which is a folded confocal cavity integrally formed by a monolithic optical element, the folded confocal cavity having three reflection surfaces, wherein a first reflection surface is a plane and at the same time serves as an input/output coupling surface, a second reflection surface is a plane, and a third surface is a spherical surface, curvature radius of which is equal to half of a round trip geometric length of light in the folded confocal cavity. The invention further discloses a laser based on the F-P cavity. The solution of the disclosure solves the problems in existing folded F-P cavity, such as unsatisfactory stability, sensitive to outside inferences, bulky and complicated construction.