Recent fluorescent single molecule experiment indicated that temperature can facilitate DNA condensation. In the spermine (spermidine)-DNA condensation system, DNA condensation conformation became more compact and orderly with increasing temperature . In order to detect the temperature effects in DNA condensation system further, a temperature-changed ultraviolet spectrum method is developed. By applying the method to the condensation system mentioned by recent fluorescent single molecule experiment and the DNA in DI water, a conclusion is derived from the absorption value at 260 nm of a condensation system will be reduced, when the corresponding system is further condensed and become compact and orderly. Based on this conclusion, effects of temperature on DNA- cobalt amine compounds used in DNA condensation experiments are detected by using temperature-changed ultraviolet Spectrum method. The results indicate that Hexaammine cobalt(Ⅲ) chloride is similar to spermine and spermidine, the UV absorption value at 260 nm of DNA reduces sharply with the temperature increasing, indicating that the DNA conformation tends to be more compact and orderly. However, for the condensation system wherein the DNA is condensed by trans (ethylenediamine) cobalt(Ⅲ) chloride, trans-dichlorobis (ethylenediamine) cobalt(Ⅲ) chloride and pentaamminechloro cobalt(Ⅲ) chloride, respectively, the UV absorption value at 260 nm of the corresponding condensation. System does not change with temperature monotonously, taking an increased-reduced-increased manner.