Farm work-related injuries are considered an important issue facing rural area adolescents. However, little research has been done in developing countries, including China. This study evaluated agricultural work-related injuries among Chinese middle school adolescents, focusing on the potential association between farm work hours, sleep patterns, school-related stress, and farm work-related injuries. This cross-sectional study surveyed 1,551 middle school students in Hunan Province who reported working on farms. The surveys assessed their involvement in farm work, sleep patterns, school activities, and farm work-related injuries during a three-month recall period. The cumulative incidence of farm work-related injury was 15.6% among the 1187 students who reported working on a farm. Average days per month farming, number of pesticide applications per month, sleep disturbances, and school-related stress were significantly associated with farm work-related injuries (p < 0.05). Multivariable logistic regression analysis revealed that after adjusting for possible confounding effects of age, gender, and farm work days per month, sleep disturbance (less than 7 hours of sleep: OR = 2.36, 95% CI = 1.07-5.22; awakening at night and having trouble falling back to sleep: OR = 2.70, 95% CI = 1.36-5.37; having nightmares: OR = 2.24, 95% CI = 1.18-4.24) and school-related stress (difficult homework: OR = 2.45, 95% CI = 1.21-4.99; extra homework assigned often by parents: OR = 3.62, 95% CI = 1.88-6.97; and scolded/chastised by parents for poor school performance: OR = 2.53, 95% CI = 1.75-3.65) were statistically significant risk factors for farm work-related injuries (p < 0.05).