The Socialist government today announced the replacement of the Army chief of staff following a public row over proposed cuts in France's conventional armed forces and a renewed emphasis on its independent nuclear deterrent.

The chief of staff, Gen. Jean Delaunay, became a controversial figure here last December when the French press obtained a confidential letter he had written opposing a plan to reduce Army manpower by 10 percent and freeze a modernization program. He was also critical of a planned reorganization of the command structure of the armed forces that will have the effect of reducing the authority of the Army chief of staff.

In a statement after today's weekly Cabinet meeting, Defense Minister Charles Hernu put the general's replacement in the context of the priority now being given to building up France's nuclear forces. He hinted that the former chief of staff, who was asked to retire 10 months early, had been unable to accept the reform of "certain archaic structures" in the Army.

According to leaks in the French press, the Army has been told that its manpower will be reduced by about 35,000 men in the present decade. The 1st Army, which is stationed in West Germany and serves as a potential reserve for NATO, could be among the units most affected. Defense chiefs were also alarmed by the announcement last year of a freeze on capital expenditure worth $2 billion for Mirage jets, AMX10RC tanks and 155 mm artillery.

These projects were described by Delaunay in his confidential letter leaked last year as being likely to result in an Army "with fewer men, weaker structures, older equipment, and diminished morale." He demanded that the "very heavy" sacrifices be reconsidered.

Addressing a farewell parade today, Delaunay alluded to the reasons for his dismissal when he said: "I am leaving the Army not in order to abandon you, but in order to protect you." This remark implied that his campaign against the cuts, which has been supported by right-wing opposition parties in the National Assembly, would continue.

Opposition fears that France's conventional forces are deliberately being run down to save money have already provoked a full-scale censure debate in the National Assembly.

For most analysts, however, President Francois Mitterrand's preoccupation with building up France's force de frappe is more reminiscent of the policy followed by the late general Charles de Gaulle. Like de Gaulle, Mitterrand believes that France's security and the overall balance of power in Europe are inextricably linked with the possession of a powerful, independent nuclear deterrent.

Delaunay was appointed to the post of chief of staff in October 1980 by Mitterrand's predecessor, Valery Giscard d'Estaing. His replacement is Gen. Rene Imbot.