The invention provides a wearable smart ring capable of capturing three-dimensional postures of the four limbs of a human body. The wearable smart ring comprises a joint wearable fixing device worn at a joint position of a human body, wherein an upper connecting rod fixing block and a lower connecting rod fixing block are respectively fixed on an upper connecting rod and a lower connecting rod at the joint position of the human body; an upper connecting rod shaft is connected with the upper connecting rod fixing block; the lower connecting rod shaft is connected with the lower connecting rod fixing block; a joint encoder is used for detecting the joint rotating angle of the human body, a flange is connected with the upper connecting rod shaft, and a rotating shaft is connected with the lower connecting rod shaft; an upper connecting rod gyroscope is used for detecting the spacial rotating direction at the upper connecting rod of the human body; and a joint fixing device end wireless CAN bus is connected with the joint encoder and the upper connecting rod gyroscope respectively and used for transmitting signals of the upper connecting rod gyroscope and signals of the joint encoder. The wearable smart ring has the characteristics of accurate joint angle measurement, precise and timely angle reading, high adaptability, long transmission distance, real-time transmission and the like and effectively solves the problem of data reading delay.