  Probabilistic behavior is omnipresent in computer controlled systems, in
particular, so-called safety-critical hybrid systems, because of various
reasons, like uncertain environments, or fundamental properties of nature. In
this paper, we extend existing hybrid process algebra $ACP_{hs}^{srt}$ with
probability without replacing nondeterministic choice operator. In view of some
shortcomings in existing approximate probabilistic bisimulation, we relax the
constrains and propose a novel approximate probabilistic bisimulation relation.
After that, we present a performance evaluation language, CTRML, to reason over
probabilistic systems, which extend the results to real number. Along with the
specification language, we present a set of algorithms for the evaluation of
the language. Additionally, we transfer the hybrid process algebra to
probabilistic transition system and show experimental results.
