Thiamine derivatives of thiamine tetrahydrofurfuryl disulfide (TTFD) and thiamine propyl disulfide (TPD) were obtained in a good yield and purity by use of thiothiamine (SB₁) and also described in details for the preparing sodium tetralrydrofurfuryl thiosulphate (Bunte`s salt)with and without KI. The optimum reaction conditions for the preparation of TTFD was set in which the Box-Wilson plan was applied. The reaction conditions are as follows; 1. pH value of aqueous solution of thiol type of B₁·HCl;12.09 2. Quantity of Bunte`s salt (to B₁·HCl 20G); 35.01g 3. Reaction temperature; 15.59℃ Studies on ultraviolet absorption were made at various pH and showed that the absorption maxima are shifted with change of pH. The absorption maxima are at 244∼246㎚, 234∼235㎚ in TTFD, and 245∼246㎚, 233∼235㎚ in TPD. The structure was proved by the infrared spectral evidence. Quantitative determination vans studied.