Unreasonable and illegal, can be simply calculated. If the principal is 1 1,000 yuan, 1% per day is 1 1,000 yuan; A month is 30%, which is 3000 yuan; Converted into a monthly interest rate of 30 cents, the highest monthly interest rate stipulated by the Supreme Law has two standards, one is 2 points and the other is 3 points. That is, everything within 2 points is legal; Between 2 and 3, the state does not interfere; More than 3 points is illegal. In your case, the monthly interest rate is already 30 points, which is ten times higher than 3 points. Legal basis: Article 47 of the Price Law of People's Republic of China (PRC), the state administrative organs shall collect fees according to law, strictly control the charging items, and limit the charging scope and standards. The specific measures for the administration of fees shall be formulated separately by the State Council. Interest rates, exchange rates, insurance rates, securities and futures prices shall be governed by relevant laws and administrative regulations, but this Law shall not apply. Article 680 of the Civil Code of People's Republic of China (PRC) prohibits high-interest lending, and the lending rate shall not violate the relevant provisions of the state. If there is no agreement on the payment of interest in the loan contract, it shall be deemed that there is no interest. If the loan contract does not specify the payment method of interest, and the parties cannot reach a supplementary agreement, the interest shall be determined according to the local or the parties' trading methods, trading habits, market interest rates and other factors; Loans between natural persons are regarded as interest-free.