This　paper　investigates　the　cooperative　output　regulation　problem　for　discrete-time　linear　multi-agent　systems　over　randomly　switching　network　governed　by　a　time-homogeneous　Markov　chain.　We　show　that,　based　on　the　certainty　equivalence　principle,　the　recent　developed　distributed　observer　based　feedforward　control　also　applies　to　the　Markov　randomly　switching　network.　The　stability　analysis　of　the　stochastic　closed-loop　system　is　conducted　by　the　expectation　form　of　Lyapunov　function　instead　of　the　traditional　quadratic　form.　©　2018　IEEE.