The invention discloses a testing device for the creep performance of a material under the coupling action of multiple factors, comprising a bracket, a weight, an annular heating sleeve, a first container, a strain demodulator, a power source, a temperature controller, a sealing film and a first test piece, wherein the bracket comprises a first bearing plate, a second bearing plate, a bottom plate, a first supporting rod and a second supporting rod; the sealing film is fixedly connected on the second bearing plate and the bottom plate; the weight is located on the first bearing plate; the annular heating sleeve is covered at the outside of the second bearing plate and the bottom plate; the first test piece is located in the center of the bottom plate; a first strain sensor is stuck to the first test piece and connected with the strain demodulator; the power source is connected with the power input end of the temperature controller; and the output end of the temperature controller is connected with the annular heating sleeve. The accuracy of a test result can be ensured by using the testing device. Meanwhile, the invention also discloses a testing method using the testing device; and the testing method is simple and easy to operate and capable of ensuring that the test piece has no strain looseness in the process of applying a load for a long term.