Abstract: In recent years, debt in arrears to small and medium-sized enterprises have become a serious social problem, which needs to be solved urgently. Since the default of debt involves the contractual legal relationship between the parties, the fundamental solution to this problem cannot be separated from the means of contract law. Contract law should be equipped with a general mechanism for the prevention and punishment of delinquency, which consists of two main instruments. The first instrument is to limit the agreed scope of the payment period to prevent the debtor from abusing the freedom of contract, the second instrument is to increase the defaulting party's liability for breach of contract, the feasible measures are to increase overdue interest and to grant creditors an additional fixed sum of compensation. This article provides suggestions for specific legal provisions and legislative reasons.