1. A method for exchanging information about available member engines from a first search server to a second search server for mobile searching, comprising: sending, by the first search server, a first information list of a first group of member engines to the second search server, wherein each member engine provides a real search service for one or more operator's subscribers and are generally described with meta-index information for indexing therewith; selecting, by the second search server, from the first information list of the first group of member engines, a second group of member engines that are to exchange information with the second search server; based on the selected second group of member engines, generating, by the second search server, a second information list of a second group of member engines for requesting meta-index information for indexing to the second group of member engines; sending, by the second search server, the second information list of the second group of member engines to the first search server; receiving, by the first search server, the second information list of a second group of member engines; and sending, by the first search server, meta-index information for the member engines in the second information list of the second group of member engines to the second search server for the second search server in subsequent indexing to one or more of the member engines in the second group of member engines.