For competitive sports, the key to achieving excellent athletic performance lies in how to train scientifically and arrange the training load, as well as how to use scientific means to monitor the training load in a comprehensive manner, and the booming development of wearable sensors is expected to promote the development of this field. Therefore, this paper proposes a multi-sensor based training load monitoring system for athletes, and develops a flexible wearable intelligent non-invasive device with high safety, flexibility and portability for monitoring the movement and changes in corresponding physiological parameters of the human body. The device is based on a Bluetooth 5.0-enabled processing chip manufactured by a company, as well as temperature and humidity sensors, heart rate and blood oxygen sensors, and all components are integrated on a flexible substrate. The device can effectively measure the subject's heart rate, blood oxygen data and current respiratory status by simply sticking it on the skin area under the nose, which is harmless to the human body and greatly improves the comfort of the athletes. At the same time, this paper compares the test results with the commercially available finger-clip heart rate and blood oxygenation devices, and verifies the stability and reliability of the whole system. This study provides a new program for monitoring the changes of physiological parameters caused by cerebral infarction and cardiac infarction in the course of athletes' training as more portable as possible, which is of positive significance for the development of flexible athletes' training load monitoring.