All pupil are measured: Height stand (cm), sitting height (cm) in height and measure around the chest (cm) using a tape measure, measure body weight by weighing table with an accuracy of ± 0, 1 cm; Pignet index Results: The body weight of ethnic H' Mông male pupil increased from 29, 8±1, 01 kg at age 12 to 44, 08 ±3, 2 kg at age 15; for female pupil from 30, 33 ±1, 24 at age 12 to 44, 08 ± 2, 7 kg at 15.