The invention discloses a house size measurement device based on a depth camera. The device comprises a rotatable and stretchable depth camera bracket which has a height and posture adjustment function, a computer which extracts a plane from depth information by adopting an RANSAC-based method and calculates out corresponding coordinate and angle information by using plane equation parameters, a depth input module which is arranged on the rotatable and stretchable depth camera bracket and is used for acquiring depth information in real time and transmitting the depth information to the computer, and a display screen which is in signal connection with the computer and is used for displaying the size information of the wall body and the house and performing human-computer interaction. The invention further discloses a house size measuring method based on a depth camera. The defects in the prior art are overcome. The house size measurement device and method based on a depth camera provided by the invention have the advantages of easy operation, time saving and labor saving and high safety, and can improve the measuring precision and speed.