To　abandon　a　large　number　of　low　signal-to-noise　ratio　data　or　normal　data,　the　health　monitoring　strategy　for　bridge　considering　signal-to-noise　ratio　and　vehicle-bridge　interaction　was　proposed.　Hence,　the　computing　resources　were　saved　effectively　and　the　targeted　monitoring　based　on　theory　was　realized.　The　composition　of　the　vibration　signal　was　discussed,　and　the　reasonable　and　accurate　monitoring　threshold　was　determined　according　to　vehicles-bridge　interaction　dynamics.　A　time-varying　dynamic　car　group　model　which　included　a　main　uniform　parameters　and　coupling　mass　was　established.　The　dynamic　coupling　equations　for　bridge　and　car　group　were　established　and　the　analytical　expression　was　given.　For　example,　the　health　monitoring　for　a　simply　supported　beam　was　discussed.　The　dynamic　response　under　different　uniform　mass,　speed　and　vibration　frequency　of　the　car　group　was　analyzed　based　on　vehicles-bridge　interaction　theory.　The　monitoring　threshold　was　determined　according　to　simulated　result　and　measured　signal,　and　the　monitoring　strategy　was　realized.　Results　show　that　the　monitoring　strategy　is　feasible.