The
Swiss Football Association (ASF/SFV) had 28 member clubs at this time which were divided into two divisions of 14 teams each. The teams played a double
round-robin to decide their table positions. Two points were awarded for a win, and one point was awarded for a draw. The top tier (NLA) was contested by the top 12 teams from the
previous 1968–69 season and the two newly promoted teams
FC Wettingen and
FC Fribourg. The champions would qualify for the
1970–71 European Cup and the last two teams in the league table at the end of the season were to be relegated. The second-tier (NLB) was contested by the two teams that had been relegated from the NLA,
Sion and
Luzern, the teams that had been in third to twelfth position last season and the two newly promoted teams
FC Martigny-Sports and FC Langenthal. The top two teams at the end of the season would be promoted to the
1970–71 NLA and the two last placed teams would be relegated to the
1970–71 Swiss 1. Liga. ==Nationalliga A==