The invention discloses an interactive projection apparatus, which includes a control device, a projection device, an image acquisition device, and an interactive pen, wherein position identification unit of the control device employs a position identification image to identify installation mode of the projection device, and the position identification image is longitudinally asymmetric about its horizontal centerline, and is laterally asymmetric about the vertical centerline. The invention also discloses a positioning method of the interactive pen of the interactive projection apparatus: projecting the position identification image onto the projection plane; collecting the position identification projection image on the projection plane; identifying the installation mode of the projection device according to the relationship between the position identification projection image and the position identification image; collecting the coordinate of the position pointed by the interactive pen on the projection image, and calculating the corresponding coordinate on the image to be projected. The invention allows automatic correction before or after the identification of the installation mode of the projection device, by projecting the correction image and collecting the correction projection image on the projection plane, and then performing correction of the coordinate of the correction projection image against the corresponding coordinate of the correction image.