Frailty, which involves low physical activity (PA), is as a well-established factor of increased risk of hospitalization, disability, and mortality. To date, there are no specific tools to assess PA among Chinese elderly. As part of the Beijing Longitudinal Study of Aging (BLSA), we aimed to develop the BLSA Leisure-Time Physical Activity Questionnaire (BLSA-PAQ) and assess its prediction of mortality. Longitudinal study. Community. 1810 Chinese older adults completed the BLSA-PAQ questionnaire. BLSA-PAQ questionnaire containing four items: walking, outdoor chores, low-intensity exercise, and moderate-intensity exercise. Physical function was assessed through the balance test, chair-stand test, and the activities of daily living (ADL), and instrumental activities of daily living (IADL). Frailty was evaluated using a modified frailty phenotype and frailty index. The following equation was obtained based on the 8-year mortality for the four BLSA-PAQ components: BLSA-PAQ index (BLSA-PAQ total score) = Walking score + Outdoor chores score + 2 x (low-intensity exercise score) + 3 x (moderate-intensity exercise score). The BLSA-PAQ index decreased with age, and was negatively related to modified frailty phenotype score and frailty index. Low PA and pre-low PA statuses were associated with poorer results in the balance and chair-stand tests, ADL dependency, IADL dependency, and frailty. After adjusting for age and gender, the 8-year mortality HRs were 1.453 (95% CI, 1.166-1.811) and 2.358 (95% CI, 1.856-2.995) for low PA and pre-low PA, respectively. Low PA defined by the BLSA-PAQ index was associated with frailty, disability, worse physical function, and higher mortality. The BLSA-PAQ seems to be a reliable tool to measure PA in Chinese older adults. Further studies are needed to confirm these findings and validate the use of the BLSA-PAQ for frailty assessments of older adults.