legal analysis: it belongs to fraud. Forge the signature of the guarantor, the validity of the guarantee contract is to be determined, and it will not have legal effect on the guarantor without ratification by the guarantor. If so, it may be suspected of loan fraud; In addition, from a civil point of view, it means that there is no actual guarantor. Forging signatures and fingerprints belong to forging evidence, and legal responsibilities can be investigated respectively according to the purpose and circumstances of forging evidence. Guarantee often appears in the behavior of loan, which belongs to capital turnover. In life, if this behavior is not used in bad places, it is very useful. The reasons why the contract is invalid are: one party concluded the contract by fraud or coercion, which harmed the national interests. Malicious collusion harms the interests of the state, the collective or the third party. Cover up illegal purposes in a legal form.

Legal basis: Article 111 of the Civil Procedure Law of the People's Republic of China, if a litigant participant or other person commits one of the following acts, the people's court may impose a fine or detention according to the seriousness of the case; If the case constitutes a crime, criminal responsibility shall be investigated according to law: (1) forging or destroying important evidence, which hinders the people's court from hearing the case; (2) using violence, threats or bribes to prevent witnesses from testifying or instigating, bribing or coercing others to commit perjury; (3) Hiding, transferring, selling off, destroying the property that has been sealed up or detained, or transferring the property that has been counted and ordered to be kept; (4) insulting, slandering, framing, beating or retaliating against judicial personnel, participants in litigation, witnesses, translators, expert witnesses, inspectors and people who assist in execution; (5) Obstructing judicial personnel from performing their duties by violence, threat or other means; (6) Refusing to perform a legally effective judgment or ruling of the people's court. The people's court may impose a fine or detention on a unit that commits one of the acts specified in the preceding paragraph; If a crime is constituted, criminal responsibility shall be investigated according to law.