Pig farming systems in Vietnam are very diverse but little is known about this diversity. In particular, the different livestock farming systems currently in operation do not have the same capacity to be sustainable. The study aims to categorize farming systems involving pig production and investigate their sustainability. Data were collected from 160 family pig farms and 2 large-scale farms in Mai Son district of Son La province (northwest of Vietnam) using stratified random sampling. The multiple factor analysis method was used to identify different farms and to characterize each type with economic, social, and environmental indicators. The results highlighted four different farm types. Type 1 contained smallholder farms with diversified farm activities. They were mainly farmed by ethnic minorities located in the intermediate highland. They had low labor productivity and relied mainly on crop farming. Pig production was characterized by a low level of economic and social sustainability. Type 2 farms had comparatively less land and crops than other types. They were more specialized in livestock production, had medium-size pig herds, and were engaged in off-farm jobs. They were less dependent on credit or location and performed better with regard to environmental issues than larger farm types. Type 3 was specialized farms with large pig herds. They seemed more sustainable in economic and social components than the other types, but their environmental sustainability was questionable. Type 4 contained large mixed crop-livestock farms. They obtained high income but were more dependent on credit than the other types. In the future, in addition to focusing on large-scale specialized farms, policies should also consider small-scale and diversified farms because of their role in the sustainable development of national pig production.