A method for obtaining sign data of a target object, comprising: obtaining a 3D depth image of a target object, wherein the 3D depth image is a two-dimensional image with distance information, and the distance information comprises a distance between the target object and an imaging device; obtaining, according to depth values of pixels in the 3D depth image of the target object, human body framework parameters and a graphic contour that are of the target object, wherein the depth value is a distance that is between a point on the target object and the imaging device and that is obtained according to the distance information; retrieving a 3D model matching the human body framework parameters and the graphic contour that are of the target object from a 3D model library, and obtaining a parameter ratio of the 3D model, wherein the parameter ratio is representative of a ratio of a distance between any neighboring and interconnected nodes in each part of a human body framework; obtaining at least one real size of the target object; and obtaining sign data of the target object according to the parameter ratio of the 3D model and the at least one real size, wherein the target object is a human body and the sign data comprises at least one of an arm length or a shoulder width of the human body; characterised in that obtaining the at least one real size of the target object comprises: transmitting a sound wave signal to the target object; receiving a sound wave signal reflected by the target object; obtaining a transmission time of the sound wave signal, wherein the transmission time is a difference between time of transmitting the sound wave signal and time of receiving the sound wave signal; calculating a distance between a surface of the target object and the imaging device by using the transmission time and a propagation velocity of the sound wave signal; and calculating the at least one real size of the target object by using the distance and a corresponding image distance of the imaging device. obtaining a 3D depth image of a target object, wherein the 3D depth image is a two-dimensional image with distance information, and the distance information comprises a distance between the target object and an imaging device; obtaining, according to depth values of pixels in the 3D depth image of the target object, human body framework parameters and a graphic contour that are of the target object, wherein the depth value is a distance that is between a point on the target object and the imaging device and that is obtained according to the distance information; retrieving a 3D model matching the human body framework parameters and the graphic contour that are of the target object from a 3D model library, and obtaining a parameter ratio of the 3D model, wherein the parameter ratio is representative of a ratio of a distance between any neighboring and interconnected nodes in each part of a human body framework; obtaining at least one real size of the target object; and obtaining sign data of the target object according to the parameter ratio of the 3D model and the at least one real size, wherein the target object is a human body and the sign data comprises at least one of an arm length or a shoulder width of the human body; transmitting a sound wave signal to the target object; receiving a sound wave signal reflected by the target object; obtaining a transmission time of the sound wave signal, wherein the transmission time is a difference between time of transmitting the sound wave signal and time of receiving the sound wave signal; calculating a distance between a surface of the target object and the imaging device by using the transmission time and a propagation velocity of the sound wave signal; and calculating the at least one real size of the target object by using the distance and a corresponding image distance of the imaging device.