The dense grooves grating and long camera focus are usually used to obtain high optical resolution in traditional Rowland and Czerny-Turner spectrometers.To avoid expensive cost or large volume of spectrometers,a novel optical system based on echelle and low dispersion prism with high optical resolution is presented.Firstly,the principle and application method of echelle are deduced in details.Secondly,the design steps are provided to set up a optical system with echelle.Finally,an optical system example based on echelle grating is designed.Its camera focus is 400 mm with wavelength range of 180~800 nm,the spectrograph can be imaged on the two dimension area at the same time .The ray tracing and optimization to the optical system are carried out with Zemax software,and the results show the encircle energy in a single CCD pixel (24 mm×24 mm) area can reach 50%~70% above within wavelength range of 180~800 nm,the resolution is 0.00675 nm at 200 nm,and it is enough to meet applications of distinguishing most elements.