Straight flush is one of the strongest hands in poker which interests many players in Vietnam. The cards in this hand consist of five consecutive cards of the same suit. For example, 5-6-7-8-9 of clubs. When talking about straight flush rule, players in Vietnam refer to the custom defining the value and drawing of this set. A straight flush beats almost any combination except the royal flush. By straight flush rule, if several people have straight flush, the one with the highest combination will always win. Although it is not possible in practice, it is important to remember. In the poker community in Vietnam, by considering this rule-set players can increase their chances of winning and ultimately make better betting decisions. Also, players can without directly controlling their winning chances avoid unnecessary arguments at splitting the pot. Therefore, knowing the straight flush rule is crucial in the VN market for all poker professionals.