On-line seat-picking method and system, and overload protection device

The invention relates to an on-line seat-picking method and system, and an overload protection device. The method comprises: monitoring connection requests sent to a same original ticketing system by each ticketing system; determining whether the number of times of connection requests within a set time exceeds a preset threshold value; if the number of times of connection requests exceeds a preset threshold value, intercepting the connection requests and starting an overload protection mode, otherwise transmitting the connection requests to an original ticketing system; responding to the interception of the connection requests, and querying whether a required seat map exists in the buffer memory of an on-line seat map; if a required seat map exists in the buffer memory of an on-line seat map, determining whether the required seat map is available according to the survival time of the seat map; feeding back data to a corresponding user if the required seat map is available; and applying for a token to access the original ticketing system if the required seat map is not available or is not stored; and responding to token obtainment, obtaining the required seat map from the original ticketing system, and selecting seats according to the obtained seat map. According to the invention, the access pressure to an external original ticketing system under high concurrent pressure can be reduced.