The invention discloses an interference filtering method under a touch mode in a projection interaction system. The method comprises the steps that an infrared image containing a projection screen finger touch moment is collected in real time; the infrared image is preprocessed to obtain multiple connected domains; according to the shape and size of the connected domains, screening is performed onthe connected domains to obtain n qualified connected domains; pixel-by-pixel traversal is performed on the n qualified connected domains to obtain a central position and a long-axis direction of allthe connected domains; according to the central position and the long-axis direction of all the connected domains, normalization processing is performed on all the connected domains; a luminance histogram of each connected domain obtained after normalization processing is extracted, and similarity values of all the luminance histograms and m finger region luminance histograms pre-stored in a database are calculated one by one; the obtained luminance similarity values are compared with a set luminance similarity threshold; and the connected domains belonging to a finger region are screened outof the n qualified connected domains. Through the scheme, the finger region can be accurately recognized.