A swimming posture correction method and a swimming posture correction system, adapted for a computing apparatus to correct a swimming posture of a swimmer using at least two gravity sensors, are provided. The gravity sensors are respectively disposed at ends of at least two limbs of the swimmer performing a relative stroke action. In the method, body parameters of the swimmer are obtained and a reference index of coordination for implementing a swimming posture suitable for the body parameters is captured. A stroke of the limb is monitored using the gravity sensors to obtain a timing diagram of the limbs performing a stroke promotion action. Then, an index of coordination of the swimmer is calculated by analyzing the timing diagram and compared with the reference index of coordination so as to prompt for correcting the swimming posture according to a comparison result.