  We present the analytic calculation of two-loop master integrals that are
relevant for $tW$ production at hadron colliders. We focus on the integral
families with only one massive propagator. After choosing a canonical basis,
the differential equations for the master integrals can be transformed into the
$d$ln form. The boundaries are determined by simple direct integrations or
regularity conditions at kinematic points without physical singularities. The
analytical results in this work are expressed in terms of multiple
polylogarithms, and have been checked with numerical computations.
