Under　the　condition　of　random　communication　delays,　this　paper　deals　with　the　problem　of　fault　detection　for　networked　switched　systems　with　arbitrary　switching　laws.　The　delay　of　data　packets　include　the　measured　output　and　the　switched　signal　and　the　delays　satisfy　the　Bernoulli　random　binary　distribution.　By　using　multiple　Lyapunov　function,　a　general　observer-based　fault　detection　filter　is　designed　and　applied　as　the　residual　generation　system.　Then　the　design　of　fault　detection　filter　is　formulated　as　H　infinity　filtering　problem　in　terms　of　H　infinity　theory.　Sufficient　condition　for　the　existence　of　the　filter　is　established　by　means　of　linear　matrix　inequalities　(LMI)　at　last.　A　numerical　example　shows　the　validity　of　the　proposed　method.