The present study aims at finding out the developmental trend of motor abilities of Chinese infants from one to two years old. The subjects were 450 healthy infants who were selected from public hospitals and various district health centers. They were further divided into 12, 15, 18, 21 and 24 months groups. The basic factors of selecting sample were sex and family social-economic status. Bayley´s Infant Scale of Motor Development was used as the instrument of measurement, Each subject was tested individually in the observation room located in National Taiwan Normal University. The following results have been found. 1. As regarding to the developmental trends of motor abilities of Chinese infants from one to two years old. We have computed the means and standard deviations of motor scores of infants from each age group and percentages of subjects in each age group who has passed each item of Bayley´s scale of motor dovelopmont. Generally speaking, almost all the subjects of 12 months could sit down and stand up. Between age of 12 to 15 months, the subjects could walk alone, walk on side and walk backward. Between the age of 15 to 18 months, the subjects could go upstairs and downstairs with the help of adult. Between the age of 18 to 21 months, the subjects could walk upstairs without help. Being able to walk on a line of 10 feet long is a motor skill which was too difficult for infants of two years old. 2. The results were also indicated that the age of the subject and their body length were two most important factors to predict motor development of infants. 3. Both mental and motor development in the early years were significant related. Socio-economic status, sex and birth-order of the subjects were not related to their motor development. 4. Comparable growth patterns were found between the motor development of Chinese and American infants.