Food industry plays an important role in meeting economic development goals and increasing demands of processed food. However, there have been no studies considering the performances of food industry over time was found in Vietnam. Therefore, the study used a data set of 340 food processing companies from the small and medium enterprise (SME) surveys in 2007, 2009 and 2013. By applying latent class stochastic frontier analysis for a balanced panel data, the study found that the average technical efficiency of food processing companies was 91.5%, suggesting that they could expand their output level about 9% while keeping inputs constant. The study also found that the technical efficiency has been improved over time at annual growth rate of 1.47%. The firms in Ha Noi, Ho Chi Minh and Quang Nam had the lowest technical efficiency score while that of the firms in Lam Dong, Hai Phong and Ha Tay provinces were the highest.