The membrane (M) protein is the most abundant component of the porcine transmissible gastroenteritis virus (TGEV) particle. To exploit the possibility of using RNA interference (RNAi) as a strategy against TGEV infection, three plasmids (pRNAT-1, pRNAT-2, and pRNAT-3) expressing short hairpin RNAs were designed to target three different coding regions of the M gene of TGEV. The plasmids were constructed and transiently transfected into a porcine kidney cells, PK-15, to determine whether these constructs inhibited TGEV production. The analysis of cytopathic effects demonstrated that pRNAT-2 and pRNAT-3 could protect PK-15 cells against pathological changes specifically and efficiently. Additionally, indirect immunofluorescence and 50% tissue culture infectious dose (TCID50) assays showed that pRNAT-2 and pRNAT-3 inhibited the multiplication of the virus at the protein level effectively. Quantitative real-time PCR further confirmed that the amounts of viral RNAs in cell cultures pre-transfected with the three plasmids were reduced by 13, 68, and 70%, respectively. This is the first report showing that RNAi targeting of the M gene. Our results could promote studies of the specific function of viral genes associated with TGEV infection and might provide a theoretical basis for potential therapeutic applications.