The invention discloses a cat litter having the function of pet urine protein early warning and a preparation method thereof. The cat litter is prepared from modified fine pored silica gel, diatomite,active carbon, a urine protein indicator agent and an antibacterial agent. A biuret reaction is applied to the preparation process of cat litter, a silica gel substrate material and the urine proteinindicator agent are scientifically proportioned according to usage quantities so as to generate a color development reaction on urine having abnormal urine protein, no color development reaction is generated on urine with a normal value, in this way, the health conditions of a pet can be reflected primarily, the pet with the abnormal urine can be brought to see a doctor and checked in time, and the effect of early warning is realized. According to the cat litter, silica gel is further modified, the hydrophilia of the silica gel is effectively improved, the effect of dip dyeing of the silica gel with the urine protein indicator agent is enhanced, and therefore the color developing reaction is obvious and easy to distinguish. Meanwhile, the novel antibacterial agent is added, the antibacterial effect of the cat litter is remarkable, continuity is good, and frequent replacement is not needed. The preparation technology is simple, costs are low, and the cat litter is suitable for application and popularization.