The Swiss Football Association (ASF/SFV) had 28 member clubs at this time and these were devided into two divisions of 14 teams each.
The teams played a double round-robin to decide their table positions.
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.