The invention discloses a protractor capable of measuring inclined plane obliquity. The protractor comprises a protractor body on which a scale 1 which represents an angle and a center of the protractor are arranged. The protractor capable of measuring inclined plane obliquity is characterized by comprising two same protractor bodies and a slope inclination needle, the two same protractor bodies are symmetrically arranged in parallel, and a sealed slot cavity is formed between the two protractor bodies; a shaft which is vertical to the planes of the protractor bodies is fixedly arranged in the centers of the two same protractor bodies, the protractor bodies are provided with scales which represent the inclined plane obliquity and are concentrically provided with the scales which represent the angles in a coplane in parallel; 0 degree of the scales which represents the inclined plane obliquity is arranged at 90 degree place of the scale which represents the angle, the scale which represents the inclined plane obliquity is gradually increased to two side angles from the beginning of 0 degree, and the slot cavity is internally provided with an inclined plane obliquity pointer; one end of the inclined plane obliquity pointer points the scale of the inclined plane obliquity, and the other end of the inclined plane obliquity pointer is fixedly connected with an elliptic cake type metallic object.