1. A visual positioning apparatus, comprising: an image sensor, being configured to derive an image by sensing a visual code marker in a space; and a processor, being electrically connected to the image sensor and configured to execute the following operations: (a) identifying an identified marker image comprised in the image, (b) searching out a plurality of corner positions of the identified marker image, (c) deciding a marker structure of the identified marker image according to the corner positions, wherein the marker structure comprises a plurality of vertices, (d) selecting a portion of the vertices as a plurality of first feature points according to an identifier of the identified marker image, (e) searching out a second feature point from a preset searching range for each of the first feature points, (f) updating the vertices of the marker structure according to the second feature points, (g) selecting a portion of the updated vertices as a plurality of third feature points, and (h) calculating a position of the visual positioning apparatus in the space according to the third feature points.