The invention discloses a blast furnace smelting expert system built based on a pattern recognition technology, which comprises a server, an operator workstation, six sets of PLCs (programmable logic controllers) (respectively used for material preparation below grooves, material distribution at the top of a blast furnace, water granulated slag control, dust removal control, coal powder injection control and water system control), a distributed control system, an IPC (industrial personal computer) for communication, a state classification module, a state diagnosis module, a state evaluation module, a state adjusting module and a state display module, wherein the server is provided with a database, the state classification module, the state diagnosis module, the state evaluation module and the state adjusting module are arranged in the server with the database, and the state display module is arranged in the operator workstation. Meanwhile, the invention also discloses a method for building a blast furnace smelting expert system based on a pattern recognition technology, which comprises the following steps of data access, state classification, state diagnosis, state evaluation, state adjustment, state display and execution. The system and method disclosed by the invention have the characteristics of standard and objective evaluation, good integrated performance, rich knowledge base and real-time updating, and can be widely applied to the technical field of blast furnace process control.