Laser mode competition is a well-known phenomenon in a multi-mode laser system. The competition between different lasing modes is considered inevitable in all kinds of lasers. However, our experiments show that laser mode anti-competition can be observed in lasers that combine either quantum dots (QD) of different sizes or quantum wells of different composition and width. Here we report the anti-competition experiment from QD lasers. The QD structure is grown on a GaAs substrate. Two types of QD layers for 1.24μm emission and 1.28μm emission are grown alternatively in the active layer. The anti-competition behavior is observed in an external cavity laser controlled by the grating, oscillating at two different wavelengths. Experimental results show that when short-wavelength light intensity increases, long-wavelength light intensity will also increase. This is the anti-competition behavior. Nonetheless, when short-wavelength light intensity is above a certain level, long-wavelength light intensity decreases. It means that the laser behavior changes to the usual competition situation at the large intensity.