Excuse me, my company closes at 6 pm, but is it legal to work overtime after 8 pm?

Illegal. According to the Labor Law and the Labor Contract Law, the state implements a working-hour system in which workers work no more than eight hours a day and 40 hours a week on average. For workers who work by piece, the employing unit shall reasonably determine their labor quota and piecework remuneration standard according to the stipulated working hour system. The employing unit shall ensure that workers have at least one day off every week. The employing unit shall strictly implement the labor quota standard, and shall not force or force workers to work overtime in disguised form. Where the employing unit arranges overtime work, it shall pay overtime wages to the workers in accordance with the relevant provisions of the state. Due to the needs of production and operation, the employer may extend the working hours after consultation with the trade unions and workers, generally not exceeding one hour per day; If it is necessary to extend the working hours for special reasons, the extended working hours shall not exceed three hours a day and thirty-six hours a month under the condition of ensuring the health of the workers. Under any of the following circumstances, the employing unit shall pay the wages higher than the wages of the workers in normal working hours according to the following standards: (1) If the workers are arranged to extend their working hours, they shall pay the wages not lower than 150% of the wages; (2) If workers are arranged to work on rest days but cannot be arranged for compensatory time off, they shall be paid a salary of not less than 200% of their wages; (3) If workers are arranged to work on legal holidays, they shall be paid no less than 300% of their wages.