This thesis is concerned with the existence of weak solutions for second order boundary value problem for impulsive dynamic equations on time scales,and the ex-istence of nontrivial homoclinic solutions for second-order differential equations with impulses.Main results are as follows:1.Under super-linearity.Ambrosetti-Rabinowitz condition and some nonlinear impulsive perturbation,we prove the existence of weak solutions of the following sec-ond order boundary value problem for impulsive dynamic equations on time scales by using Mountain Pass Lemma: where T is a Time Scale,[0,T]T:=[0,T]∩T,σ(0)=0 andσ(T)=T.f:[0,T]T×Râ†'R,Ij∈C[R,R].{Aj},{Bj}are real sequences which satisfy:Bj=(1+ Aj)â†'-1 and∑k=1 p|Ak|<1,the impulsive points tj∈[0,T]T are all right-dense,and 0=to |