Squid (Ommastrephes bartrami) from Northern Pacific, its muscle of body changes in shrink, weight, moisture and total nitrogen were studied when it was heated in boiling water. It is found that the body vertical change was much more than that in horizon-tal change. Maximum changes in volume, weight, moisture have been reached when the body is boiled at the 4th minute, then trending towards stability. Total nitrogen losses be-come more during heating. In order to prevent from moisture loss, hardening and nutrition loss during boiling and to optimize the operation condition, the boiling procedure should be entirely finished in 3 minutes.