This paper proposed an attention evaluation system using 8-channel differential prefrontal EEG signals acquired from the forehead. A 16-channel neural signal acquisition module was designed and fabricated in TSMC 180nm CMOS process. It consists of chopper LNAs, switched-Capacitor programmable gain amplifiers and 12-bit SAR ADC. The proposed digital attention evaluation algorithm was implemented on FPGA, including IIR filters, calculation of the filtered neural signal strength indicator, SVM-based classifier.