Legal analysis: it is 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. Forged signatures and fingerprints belong to forged evidence, and legal responsibilities can be investigated according to the purpose and circumstances of forged evidence. Guarantee often appears in loan behavior, which belongs to capital turnover. In life, if this behavior is not used in bad places, it is very useful. The reason why the contract is invalid is that 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 a third party. Cover up illegal purposes in a legal form.

Legal basis: Article 111th of the Civil Procedure Law of People's Republic of China (PRC). 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 or 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 assisting executors; (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 listed in the preceding paragraph; If a crime is constituted, criminal responsibility shall be investigated according to law.