The invention relates to a titanium oxyoxalate electrorheological fluid and a preparation method thereof. The titanium oxyoxalate electrorheological fluid is characterized by using titanyl oxalate particles in nanometer to micron sizes as a dispersing phase and uniformly dispersing in silicon oil to form the suspended liquid. The titanyl oxalate particles in the suspended liquid have the volume concentration of 5-40 percent. The preparation method of the titanium oxyoxalate electrorheological fluid comprises the following steps of: firstly, carrying out a chemical precipitation reaction of oxalic acid and titanium of the same mol number in an alcohol solvent to prepare titanyl oxalate particles; uniformly mixing the titanyl oxalate particles with the silicon oil; and obtaining the titanium oxyoxalate electrorheological fluid. The titanium oxyoxalate electrorheological fluid provided by the invention has strong electrorheological effect, reaches the stress yield of 120kPs and the dynamic shearing stress of 40kPa when an external electric field is 5kV/mm, has the advantages of small current density, no toxicity, environmental protection, and the like and has favorable application prospects. Moreover, the needed raw materials are easily obtained and have low cost, and the preparation process is simple and has short cycle.