The invention discloses an automatic projection method applied to a projection robot. The method comprises the steps of imaging a periphery from different angles, thereby generating a plurality of environment images; carrying out image analysis on the plurality of environment images, thereby determining at least one crowd and the corresponding number of people and crowd orientations; determining whether at least one target crowd of which number of people and crowd orientations satisfy a first predetermined condition exists or not, if the at least one target crowd exists, determining any target crowd as a viewing side, otherwise, selecting a first crowd from the at least one crowd and moving the projection robot relative to the first crowd until the viewing side is determined; and projecting predetermined content on a projection wall surface out of the viewing side. The invention also discloses the projection robot. Through application of the scheme provided by the invention, the projection robot can be automatically moved near to an ideal projection point according to the crowd distribution condition.