This paper introduced the design of digital clock with the function of temperature display. We use the chip of DS1302 as the part of time running, the chip of DS18B20 as the part of temperature detecting, and the LCD12864 as the part of time and temperature display. We can adjust the time by keyboard. The interface of this circuit is simple, and the electron device we used is rather cheap. And you may get started quickly of the operation of the clock. The system uses the production of the Microchip cord-PIC16F877 as the microcontroller. The design includes the drive of PORTA, PORTC, PORTD and PORIE as general digital ports. We use the pins of RAO, RA1, RA2 to control the LCD and all the pins of PORTC to deliver needed data or command of LCD. We use the 3 pins of REO, RE1, RE2 to control or receive the data of DS1302, and we adopt the BURST MODE of DS1302 to set and receive the data of time. We use the pin of RA3 as the 10 port of DS18B20 to initialize the chip and get the data of temperature. Finally, we use the 8 pins of PORTD to receive the data from the keyboard. In addition, we may adjust the clock by keyboard. In this design the functions of time and alarm clock run and change, voice broadcast, functions of the year, month, day and week display have been achieved.