Abstract: A trajectory data query method includes establishing a spatial-temporal index and an inverted index for trajectory data in a spatial-temporal database, where the inverted index is used to form a first relationship correspondence table that includes a correspondence between each trajectory and its associated index leaf node; performing sampling for an index leaf node included in a space area specified by a user, where a quantity of index leaf nodes in the space area and a quantity of index leaf nodes obtained by sampling are determined; determining, according to the index leaf nodes obtained by sampling and the first relationship correspondence table, a correspondence between each trajectory included in the index leaf nodes obtained by sampling and an index leaf node associated with the trajectory, to form a second relationship correspondence table; and determining an unbiased estimation operator according to the quantity of index leaf nodes in the space area.