In this study, we modified the acid treated carbon nanotubes (CNTs) by a series of silane compounds via sol-gel process to improve the CNTs’ dispersion stability in solvents. The silane modified CNTs were identified by Infrared and Raman spectra. In addition, the dispersion stability of silane modified CNTs were analyzed by scanning electron microscope (SEM), transmission electron microscope (TEM), BET (specific surface area analyzer), zeta potentiometer and UV-vis spectrophotometer. The results shown that silane with n-octyl group (OTES) modified CNTs (OTES-HCNTs) possess the best dispersion stability in different polarity solvents. Therefore, we prepare the screen-printed composites by blending different OTES-HCNTs contents in Poly(methyl methacrylate) (PMMA), and using differential scanning calorimetry (DSC) and thermal gravimetric analyzer (TGA) to analyze thermal properties of the composites. The thermal stability of OTES-HCNTs composites was improved with increasing the content of OTES-HCNTs. From the dynamic mechanical analyzer (DMA) analysis, the tensile strength of composites raises with increasing the OTES-HCNTs’ contents in PMMA. The surface morphology and dispersion stability of CNTs in composites are analyzed by SEM and atomic force microscopy (AFM); the results show that PMMA with 3 wt% OTES-HCNTs possess the best dispersion uniformity. The field emission properties were investigated by ultra-high vacuum array tester, which show that adding 3 wt% OTES-HCNTs in PMMA with better light uniformity, low drive electric field of 1.9 V/μm, and larger current under fixed electric field. Finally, to improve the fabricated precision of triode structure CNTs field emission display, we design the horizontal rotating spray etching mechanism, which the etchant were sprayed through the nozzle from the bottom-up to improve the etching rate. The shape of the etching holes close to anisotropic etching. Form the experimental results, the optimal process parameters were obtained as the etchant concentration of 2.2 wt%, the injection pressure of 1034 Pa. The etching factor of 0.7737 and etching patterns uniformity of 94% could be achieved under the above parameters. In the triode structure CNTs field emission display, the current intensity of 10 mA and emission uniformity of 83.85% could be received as the anode voltage of 1500 V and the gate voltage of 100 V.