Legal analysis: forging a guarantor to defraud money is fraud. You can save the evidence and report the case to the local public security organ after investigation.

The guarantee contract signed by the lender forged the signature of the guarantor is invalid, and the guarantor may refuse to undertake the guarantee obligation, and may sue the lender in the name of forged signature.

If there are multiple guarantors, only one guarantor's signature is forged, and the forgery does not affect the establishment of other guarantee relationships, the guarantee contract is partially invalid.

Legal basis: Article 388 of the Civil Code of People's Republic of China (PRC) establishes a security interest, and a security contract shall be concluded in accordance with this law and other laws. Guarantee contracts include mortgage contracts, pledge contracts and other contracts with guarantee functions. The guarantee contract is a subsidiary contract of the main creditor's rights and debts contract. If the principal creditor's rights and debts contract is invalid, the guarantee contract is invalid, unless otherwise stipulated by law.

If the debtor, guarantor and creditor are at fault after the guaranty contract is confirmed to be invalid, they shall bear corresponding civil liabilities according to their faults.