  Uncertainty principle reveals the intrinsic differences between the classical
and quantum worlds, which plays a significant role in quantum information
theory. By using $\rho$-absolute variance, we introduce the uncertainty of
quantum channels and explore its properties. By using Cauchy-Schwarz inequality
and the parallelogram law, we establish the product and summation forms of the
uncertainty relations for arbitrary two quantum channels, respectively. The
summation form of the uncertainty inequalities based on the $\rho$-absolute
variance for arbitrary $N$ quantum channels are also investigated and the
optimal lower bounds are presented. We illustrate our results by several
typical examples.
