In this paper, we study the capillary flows in square tubes and in equilateral triangle tubes under microgravity condition by performing experiments in drop tower, and also compare them with those in circular tubes. Experimental results showned the influence of both size and shape of tubes on the capillary flow driven by interfacial forces. For tubes of the same shape, the influence of tube size is quite similar. Moreover, the capillary flows in square tubes and equilateral triangle tubes have some similarity with those in circular tubes with much smaller sizes. The results are helpful for understanding the capillary flows driven by interfacial forces with different parameters. And they are also useful for independently controlling the flow velocity and the volume flow rate by choosing appropriate tube shapes under microgravity condition.