TECHNOLOGY FOCUS - COMPUTING AND CONTROL - Preferred Components: The parameter combination measuring device also comprises a connection interface, where the displaying device, the keyboard and the connection interface are respectively connected with the I/O terminals of the central processing unit. The connection interface comprises RS485 or RS232 connection interface, which is used for connecting with an upper computer controlling device.    TECHNOLOGY FOCUS - ELECTRONICS - Preferred Components: The circuit unit comprises: an under- and overload protection circuit; and a power charging and supplying circuit. The power charging and supplying circuit is formed by connecting a power charging circuit, a power supplying circuit and a voltage-stabilizing circuit, and is used for supplying a stable working power supply for the parameter combination measuring device. The pool liquid pH-measuring circuit is formed by a pool liquid pH-measuring biasing circuit composed of an R41 and R42 composition and a pH-measuring electrode J41. The pH-measuring electrode J41 is used as a signal input end of the pool liquid pH-measuring circuit for collecting the pH-parameter signal of a methane producing pool. An output end of the pH-measuring electrode J41 is connected with an input end of an amplifying circuit, where an output end of the amplifying circuit is connected with the corresponding signal input end of the A/D converter and interface circuit. The signal output end of the A/D converter and interface circuit is connected with the central processing unit, which is used for processing the process and the output through the displaying device. The methane concentration measuring circuit comprises a sensor CGQ1 and a methane concentration measuring bridge formed of resistors R20 and R21 and a potentiometer J10. The methane LEL percentage concentration measuring warning circuit comprises a sensor CGQ2, a methane LEL percentage concentration measuring bridge formed of resistors R20 and R21 and a potentiometer J10, and a buzzer. The sensors CGQ1 and CGQ2 are used for collecting the methane concentration parameter signal, and connected with the input end of the amplifying circuit after being sampled by a sampling circuit of the methane concentration measuring bridge and the methane LEL percentage concentration measuring bridge. The output end of the amplifying circuit is connected with the corresponding input end of the A/D converter and interface circuit. The sensor CGQ1 is a heat conduction sensor, and the sensor CGQ2 is a catalytic combustion sensor. The hydrogen sulfide gas concentration measuring circuit comprises an electrochemical sensor S31 and a measuring circuit. The electrochemical sensor S31 is used for collecting the hydrogen sulfide gas concentration parameter signal, where the output end of the electrochemical sensor S31 is connected with the input end of the amplifying circuit through the measuring circuit. The output end of the amplifying circuit is connected with corresponding signal input end of the A/D converter and interface circuit. The signal output end of the A/D converter and interface circuit is connected with the central processing unit. The parameter combination measuring device also comprises a temperature sensor and an interface circuit, where the temperature sensor and the interface circuit collect the temperature signal in a collecting measuring environment during the measuring process, and the other measured parameters are corrected by the central processing unit.