Limited data exist related to low birth weight (LBW) incidence and risk factors in Western China. This paper aims to assess LBW and its relationship with antenatal care (ANC) in the poor counties of Western China. A community-based study in rural Western China was conducted in 2011. A kernel distribution was used to estimate the adjusted LBW incidence, and associations between LBW and socio-demographic or maternal factors were examined using multilevel logistic regression. Among 8,964 participants, 65.7% were weighed at birth. Crude LBW incidence was 6.6% and the adjusted rate was 9.3%. The study revealed that risk factors of LBW are being female, raised within a minority group, and with a family income below the national poverty line. For maternal risk factors, LBW was positively associated with not attending at least five or eight ANC visits, not receiving any ANC during the first trimester, and not having access to assess certain ANC content (weight, blood pressure, blood test, urine test, B-scan ultrasound, and folic acid supplement). There is urgent need to promote quality ANC in poor and rural areas of Western China and to prioritize vulnerable women and children who will benefit from quality ANC.