  We consider general semilinear, multispeed Klein-Gordon systems in space
dimension two with some non-degeneracy conditions. We prove that with small
initial data such solutions are always global and scatter to a linear solution.
This result partly extends the previous result obtained by Deng, who completely
proved the 3D quasilinear case. To prove our result, we mainly work on Fourier
side and explore the contribution from the vicinity of space-time resonaonce.
