Abstract: The preparation of acetylene by means of magnesium method and lithium method, the chemical fundamental of the making of benzene using the catalysts of CiOO3-AL2O3-Sio and the process are inrtoduced in the paper. The advantage and the shortcoming of the both methods are compared. The result indicates that the operaion is simple with lithium method and the preparation of the sample is convenient, the sample is not polluted easily by air, the rate of production is high, the method is safe and reliable, but the cost is high, it has a dange to be poisoned. The measure cost is low with magnesium method, but the rate of production is low, the process is long, the sample is polluted easily by air and there is a dange of exploration, so it is believed that magnesium method is advanced than lithium method in C14 dating.