A wide bandwidth low crosstalk triplexer is designed and fabricated using silica arrayed waveguide gratings(AWGs).In order to obtain wide bandwidth for all three wavelengths whose wavelength differences are large，multimode interferences(MMIs)with different structures are used at the junction between output waveguides and Rowland circle.Using two-dimensional finite difference beam propagation method，the simulated results show that 3 dB bandwidth of the designed triplexer are up to 23 nm,23.5 nm and 25 nm for 1 310 nm,1 490 nm and 1 550 nm，respectively.The insertion losses all are 4 dB.The crosstalk is less than -40 dB for 1 310 nm，and are less than -40 dB for 1 490 nm and 1 550 nm.Using broadband light source，the measured results show that 3dB bandwidth for 1 550 nm is 23 nm.Using three independent narrowband light sources，the measured results show that the insertion losses of the three waves all are 7 dB.The crosstalk is less than -40 dB for 1 310 nm，and are less than -39 dB for 1490 nm and 1 550 nm.The measured and simulated results are basically consistent.