From　impact　excitation　vibration　tests　results　of　a　reinforced　concrete　beam　with　increasing　damage　levels,　the　upward　and　downward　maximums　of　displacement　and　acceleration　at　the　half　span　point　of　the　beam　and　the　jack　near　the　half　span　point　of　the　beam　can　be　obtained　and　the　relationships　between　the　three　kinds　of　maximums　and　load　levels　are　analyzed.　By　comparing　their　relationships,　it　is　found　that　the　downward　displacement　maximums　and　the　upward　acceleration　maximums　and　the　upward　and　downward　jack　maximums　increase　or　decrease　monotonically　with　increasing　load　levels.　It　can　be　concluded　that　such　kinds　of　maximums　can　be　used　to　estimate　the　reinforced　concrete　beam＇s　damage　degree.　The　downward　displacement　maximums　are　nearly　linear　to　the　load　levels　and　are　the　best　ones　to　be　used　to　estimate　the　damage　degree　in　the　four　kinds　of　maximums.　The　relationships　between　the　fundamental　frequencies　obtained　from　either　Fourier　Transformation　or　time-frequency　analysis　and　the　load　levels　are　curvilinear　and　the　relationships　between　the　downward　displacement　maximums　and　the　load　levels　are　nearly　linear,　thus,　using　the　downward　displacement　maximums　to　estimate　the　damage　levels　of　the　reinforced　concrete　beam　is　more　convenient　than　using　the　frequencies.