Ball　screw　feed　systems　serve　as　the　feed　components　of　machine　tools,　and　its　dynamic　characteristics　directly　affect　the　machining　quality　of　workpieces　and　reliability　of　ball　screws.　In　this　paper,　the　lateral　equivalent　dynamic　model　of　ball　screw　feed　systems　is　established　considering　the　bending　vibration　of　the　ball　screw,　nut　location,　and　joints　based　on　the　Euler-Bernoulli　beam　theory.　Subsequently,　the　dynamic　parameters　of　joints　are　identified　according　to　the　measured　dynamic　stiffness　using　the　particle　swarm　optimization　(PSO)　algorithm　with　the　determined　initial　range　of　stiffness　and　damping.　The　robustness　of　the　dynamic　model　is　verified　by　experiments　conducted　at　different　nut　locations.　In　addition,　the　nonlinear　dynamic　model　is　established　and　the　effects　of　cutting　force,　bearing　clearance,　and　nut　motion　on　dynamic　characteristics　are　investigated.　The　numerical　results　indicate　that　bearing　clearance　mainly　affects　the　equilibrium　position　of　worktable　vibration,　while　the　cutting　force　at　different　rotational　and　moving　speeds　of　the　nut　mainly　affects　the　vibration　mode　of　the　worktable,　but　the　vibration　mode　is　always　a　quasi-periodic　motion.　The　established　dynamic　model　and　numerical　analysis　results　provide　a　useful　understanding　of　the　dynamic　characteristics　of　ball　screw　feed　systems.