This paper studies the critical role of the microscope in subject formation of early 1950s People’s Republic of China. The campaign against alleged germ warfare (xijun zhan 細菌戰) in 1952 politicised the action of seeing the enemy through the discourse of science. Widely used for science education and mass mobilisation for the campaign, the microscope was at once visual technology and an apparatus of power, magnifying hidden and invisible enemies that threatened the new regime. This paper argues that “seeing the enemy” was the hygienic practice of weisheng (衛生), which took on a new meaning of abjection in the early 1950s. By looking into news reports, visual materials, and science writing from this period, this paper proposes a transdisciplinary methodology for studying PRC history that brings together psychoanalysis, visual culture studies, and the history of science and technology.