Since automatic silk reeling machine has been used in the fold, silk reeling tension has been considered to be an important matter. Such silk reeling tension affects on the physical nature of silk which would be Wire Silk in case of super high reeling velocity. This will be a report regarding with the silk reeling tension used Korean cocoon and various analyses are carried out where reached to following results. 1. Korean silk is still far from Wire Silk yet produced as general silk. 2. There is more possibility to increase silk reeling velocity if cocoon nature is improved. 3. At present, it is considered that the optimum reeling velocity is to be about 190 r.p.m. which is corresponded with 0.4∼0.5 g/d silk reeling tension. 4. This report has prepared a silk reeling tension contolling diagram against reeling velocity as shown at Figure 7. The mathematical relations between them are; A. in case of total silk reeling tension; Y=5.0831＋0.0381X(Y; total reeling tension, g/21d, X; reeling velocity, m/min) B. in case of initial silk reeling tension; Y=3.1922＋0.0175X (Y; initial reeling tension, g/21d, X; reeling velocity, m/min) 5. The main problems for the increase of silk reeling velocity is considered to be Break Down of Silk Reeling Ends caused by Cocoon Jumping or Cocoon Layer Seperation during the silk reeling work. Such troubles are concerned with the produced cocoon nature.