Nine Louisiana men met today's filing deadline for the state's Oct. 27 gubernatorial primary and will compete in what is expected to be a free-wheeling, free-spending contest to succeed Gov. Edwin W. Edwards.

The frontrunners are Lt. Gov. James E. Fitzmorris Jr. of New Orleans and U.S. Rep. David C. Treen (R-La.) of Metairie, a New Orleans suburb. Other serious contenders are state Sen. Edgar G. (Sonny) Mouton Jr. of Lafayette; Secretary of State Paul Hardy of St. Martinville; Public Service Commission Chairman Louis Lambert of Gonzales and state House Speaker E. L. (Bubba) Henry of Jonesboro.

The state constitution bars Democrat Edwards from seeking a third consecutive term. He easily won reelection to a second term in 1975.

The Oct. 27 voting will be an "open primary," in which all candidates compete against one another, regardless of party affiliation. If no one receives a majority, the first two finishers will meet in a runoff Dec. 8.

The five Democrats will be running against Treen and three minor candidates: Ken (Cousin Ken) Lewis, a Baton Rouge independent; Greg Nelson of New Orleans, the Socialist Workers Party nominee; and Luther Devine Knox of Winnsboro, a political unknown.

To qualify, candidates for the governorship and the other statewide posts that will be contested in the primary paid $750 filing fees.

Each of the six major candidates is expected to spend as much as $2 million by the first primary. A runoff effort is expected to cost the two survivors another $1 million each.

Campaigns for other statewide offices could cost as much as $400,000 per candidate.

Most of the money will go into television advertising. Political commercials have been running since spring, and, a Baton Rouge television executive said this week that "by mid-September, you won't be able to buy a spot on the closing prayer."

The trend toward bigger and bigger spending in Louisiana campaigns troubles some political veterans, including Douglas Fowler, 72, who is not running for reelection as state elections commissioner.

"We're fast approaching the day and age when the man who's got the money gets the office," he said, "and if a fellow wants to be governor, and he's worth $10 million, he'll buy his way in."

According to an independent poll taken at the end of July, Fitzmorris However, none of the other candi yet, and the state AFL-CIO executive council, a powerful political force, is cool toward Fitzmorris and Treen.

Hardy has cut himself off from big labor by supporting the state's "right-to-work" law in his television spots, and Treen led in the governor's race with 22 percent and 21 percent of the vote respectively. Lambert had 17 percent; Hardy 14 percent; Mouton 8 percent; and Henry trailed with 4 percent.

No endorsements have been made dates has advocated the repeal of the law, which was enacted in 1976 and prevents any company from forcing a worker to join a union as a requirement for employment.

Labor support is considered a sizable asset in Louisiana. In the past gubernatorial contests it has gone to Edwards and his predecessor John J. McKeithen, who also served two terms.

Fitzmorris, Treen and Hardy have staked out conservative positions, while Henry, Mouton and Lambert are regarded as the moderates in the field.

Besides the gubernatorial office, Louisiana voters will pick a lieutenant governor, a secretary of state, an attorney general, a treasurer, insurance and agricultural commissioners, a superintendent of education and an elections commissioner, as well as the entire legislature - 39 senators and 105 members of the state House of Representatives - and a host of local officials.