In this paper,a dual-mode semiconductor laser,of which the dual modes have equal peak intensity,is demonstrated.This laser is based on Fourier transform external ca vity structure (FTECS) which is fabricated using the coaxial cage.It is possible to real ize continuous tuning power output and can be used as seed source of terahertz (THz) wave sourc e in frequency mixing,and this study is of great significance for the study of multi-wavelengt h optical pulse equipment.The experimental results show that in a wide range of injected curren t from 1.45I_th to 3.85I_th,which are above the threshold cruuent of 8mA,the laser generates dual-mode output with gap of 1THz under the condit ion of closely moving mirror using piezoceramics.In this way ,the side-mode suppression ratio (SMSR) of two peaks can reach more tha n 30dB,and the difference of two peak intensities is no more than 0.07dB.We al so further research the relationship of the peak intensity of dual modes with the position of striped mirror and injected current.This stud y has a great significance on the design of miniaturization structure in the future on the rel ated fast tuning,structural stability and so on.