Abstract: In order to investigate the survival probability of insurance companies with credit risk and avoid their going bankrupt‚a ruin model with credit risk in finite discrete time under a constant interest rate was introduced and the ruin condition was given‚as well as the survival probability with credit risk in finite discrete time under a constant interest rate．By using this model‚the ruin probability and the distribution of the ruin time were derived．By the analysis of ruin probability‚the recursive formulae for the distributions of the surpluses before and at the instant of ruin‚together with the joint distribution of the two surpluses were finally obtained．

Key words: ruin, credit risk, Markov chain, interest rate, transition probability