The invention provides a method for determining a time point for shifting from steam huff and puff to steam drive. The determination method comprises the steps that (S1) multiple rounds of oil exploitation are carried out to an oil well through steam huff and puff, and first-type production parameters are measured after completion of each round of oil exploitation, wherein the first-type production parameters comprise a production-injection ratio; (S2) a relation curve between the production-injection ratios and amounts of oil exploitation days is established; and (S3) when a plus-minus sign of a tangential slope of the relation curve between the production-injection ratios and the amounts of the oil exploitation days changes during the n-th round of oil exploitation, the n-th round of oil exploitation is deemed to contain the time point for the shifting from the steam huff and puff to the steam drive, wherein n exceeds 1. When the plus-minus sign of the tangential slope of the relation curve between the production-injection ratios and the amounts of the oil exploitation days changes, the amount of oil which can be exploited through the stem huff and puff tends to be saturated, so that the steam huff and puff is shifted into the steam drive during the n-th round of oil exploitation, and further the oil exploitation is carried out through the steam drive. In this way, oil recovery efficiency and overall effects of steam injection thermal exploitation can be enhanced effectively.