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 1969–70 season and the two newly promoted teams
Sion and
Luzern. The champions would qualify for the
1971–72 European Cup, the second and third placed teams would qualify for the newly created
1971–72 UEFA 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,
FC Wettingen and
St. Gallen, the teams that had been in third to twelfth position last season and the two newly promoted teams
Vevey-Sports and
FC Monthey. The top two teams at the end of the season would be promoted to the
1971–72 NLA and the last two teams would be relegated to the
1971–72 Swiss 1. Liga. At the end of the NLA season it came to an extraordinary situation,
FC Basel finished the regular season level on points with
Grasshopper Club Zürich and so these two teams had to contest a play-off game on 8 June 1971 to decide the championship title. Grasshopper won the play-off 4–3 after extra time.
Bellinzona finished last in the table and were relegated.
Sion and
Fribourg, were level on points, both classes as second last, so they had to compete a play-out against relegation. Sion won 1–0 and remained in the top-tier and Fribourg were relegated. ==Nationalliga A==