The invention provides a preparation method of 
nitrogen-doped 
silicon-aluminum immobilized TiO2 porous 
ceramic. The preparation method comprises the steps of: carrying out reaction with water-soluble inorganic 
silicon salt as a 
silicon source, water-soluble inorganic 
titanium salt as a 
titanium source, water-soluble inorganic aluminum salt as an aluminum source, 
urea as a 
nitrogen source and cetyl trimethyl 
ammonium bromide as a template agent to obtain a suspension D, transferring the suspension to a hydrothermal kettle, carrying out 
hydrothermal reaction, after 
hydrothermal reaction is finished, washing, carrying out suction filtering to obtain filter mud, granulating and shaping the filter mud, then 
drying to obtain 
nitrogen-doped silicon-aluminum immobilized TiO2 precursor, and 
sintering the nitrogen-doped silicon-aluminum immobilized TiO2 precursor to obtain the nitrogen-doped silicon-aluminum immobilized TiO2 porous 
ceramic. According to the invention, 
urea is used as the 
nitrogen source, under hydrothermal high-temperature and high-pressure conditions, N-H bond in 
urea can replace 
oxygen in Ti-O to firmly bond in a 
chemical bond form, thus effective 
doping is achieved; and in addition, lattice 
distortion generated due to nitrogen entering TiO2 lattice can broaden photoresponse range of TiO2 and increase 
photocatalysis activity under visible light.