THE DIVISION within the administration over Mexico seems to be more than the usual passing bureaucratic squabble. Two weeks ago, in a hearing over which Sen. Jesse Helms presided, the U.S. commissioner of customs, William von Raab, and assistant secretary of state Elliott Abrams vehemently delivered a series of scathing accusations of Mexican corruption related to drug trafficking. Last week Attorney General Edwin Meese telephoned his counterpart in Mexico City to say that Mr. von Raab and Mr. Abrams were not speaking for the Reagan administration.

At one level, the dispute is over controlling drugs and how to achieve more effective cooperation with the Mexicans. Mr. von Raab and Mr. Abrams evidently feel that American denunciations of the Mexican performance will be helpful. If Mr. Meese disagrees, he is correct. That kind of public attack inevitably wounds Mexican national pride in a way that allows the drug dealers to hide behind the flag.

But there is doubtless more to Sen. Helms's hearing and his choice of witnesses. Mr. Helms has always taken a sharp interest in American policy toward Nicaragua and the repressive Marxist regime in power there. He has been much irritated by Mexico's refusal to support the American position. Perhaps one purpose of this hearing was to punish the Mexican government for its reluctance to show more rigor in its relations with the Sandinistas. Perhaps another purpose was to press the Reagan administration toward an adamant posture on Nicaragua and away from all that talk about negotiations and agreements. If Mr. Meese thinks that it's unwise to use inflammatory charges about Mexico as a weapon in a foreign policy dispute among Americans, he's right about that as well.

Mexico is going through a bad time, and its government is under great strain. For a time it lived well with the help of large foreign loans and oil revenues. But the foreign loans ended in 1982, when Mexico found itself unable to meet its debt payments, and the oil revenues dropped sharply last winter. Living standards have fallen, and there has been a precipitous decline in the loose and easy flow of money that traditionally lubricated the Mexican political system. Now, in addition, it must struggle with powerful and well-financed smuggling rings that are, from its perspective, the result of the American government's inability to control its own people's appetite for drugs.

Mr. Meese, as attorney general, has broad responsibilities to improve the enforcement of the laws against the drug trade. He seems to have decided that he can do it more effectively if the Reagan administration does not fall into a violent, abusive public quarrel with Mexico.