The invention relates to an engineering mechanical cab with an ROPS (Roll Over Protection System) protection structure, which is characterized by comprising a basic frame and an ROPS top, wherein the basic frame is mainly formed by welding a lower front cross beam, a lower right longitudinal beam, a lower left longitudinal beam and a lower back cross beam; the ROPS top is mainly encircled by an upper right longitudinal beam, an upper middle cross beam, an upper left longitudinal beam and an upper back cross beam; the lower front cross beam, the lower right longitudinal beam, the lower left longitudinal beam and the lower back cross beam of the basic frame are all welded by rectangular steel pipes; the ROPS top is encircled into a rectangle by the upper right longitudinal beam, the upper middle cross beam, the upper left longitudinal beam and the upper back cross beam, and a support inclined strut is connected to at least one opposite angle; a front right stand column and the upper right longitudinal beam are made of deformed steel pipes and are integrally bent and formed; and a front left stand column and the upper left longitudinal beam are made of deformed steel pipes and are integrally bent and formed. The engineering mechanical cab has the advantages that large type excavators can meet the ROPS standard requirement, the ROPS is not damaged under the independent or continuous effects of lateral, longitudinal and vertical loads, and generates certain plastic deformation at the same time to absorb the impact capacity, thus, the impact injury on an operator is reduced.