It depends on your relationship with your uncle and the purpose of the loan.
If you are close to your uncle and the purpose of the loan is reasonable, you can consider lending it to him. However, if you don't know much about his reputation and the purpose of the loan, you'd better consider carefully, or fully communicate and understand with him before borrowing.
In addition, if you are not sure whether to lend it to him, you'd better consult your friends or other professionals to increase the wisdom of your decision.
When your uncle asks you to borrow money, you can consider the following ways to refuse:
Direct rejection: Sometimes, direct rejection is a more effective way to avoid unnecessary trouble. You can tell your uncle that you don't have enough money now, or you need to consider your financial situation before deciding whether to lend it to him.
Find reasons to be poor: Sometimes, you can find some excuses to be poor to refuse your uncle. For example, you can say that you are still in debt, or that you have spent all your money, or that you have lent money to others, so that they can borrow money from others.
Reverse borrowing: you can consider borrowing money from your uncle when he comes to borrow money from you, and say: "What a coincidence, I need money urgently. You see, we have such a good relationship, can you lend me some money first?".
No matter which way you choose, you should stick to your own principles and bottom line, and be polite and honest. At the same time, you can also try to persuade your uncle to understand your dilemma and be willing to give you some time to solve your own problems.