High quality and large-size single crystals of CaTi2O4 were prepared by the molten salt flux method. The X-ray diffraction and the EDS results showed that all the CaTi2O4 crystals have the rom temperature lattice parameters a=9.781 ?,b=9.966 ? and c=3.148 ?, and all the samples have perfect stoichiometric composition. Through the magnetic susceptibility measurement, we first obtained the Van-Vleck paramagnetic parameter of CaTi2O4 of 6.85×10－5cm3/mol, and Cure-Weiss temperature of -0.44 K, revealing that CaTi2O4 is a weak ferromagnetic compound. Further more, the existence of Ti-Ti dimer was confirmed by anisotropy measurement, the structure and direction of the antiferromagnetic dimer chains were also determined.