Speaker Jim Wright (D-Tex.) yesterday completed the selection of House members to take part in the House-Senate conference on the trade bill, which he said he would like finished by the end of October.

The naming of the full group of 155 House members who will join 44 senators in the conference allows Congress to begin work on melding two massive trade measures into one bill that can be sent to the president.

Wright gave control of the conference on the House side to Rep. Dan Rostenkowski (D-Ill.), chairman of the Ways and Means Committee, which has primary jurisdiction over trade.

Rostenkowski also will be chairman of the entire conference, with Senate Finance Committee Chairman Lloyd Bentsen (D-Tex.) serving as vice chairman.

The conference, involving 14 committees from the House and nine from the Senate, is one of the largest and most complex in congressional history.

Selecting the members required resolving turf battles between committee chairmen, especially one between Rostenkowski and John Dingell (D-Mich.) of the Energy and Commerce Committee, which is trying to move into the trade area.

Rostenkowski will have to oversee a myriad of subgroups dealing with specific sections of the trade bill.

As an example of the complexity of the conference, the House Banking Committee has set up 23 subgroups.

Moreover, four House panels -- the Armed Service, Foreign Affairs, Government Operations and Ways and Means committees -- will be dealing with one provision in the Senate version of the bill to penalize Toshiba Corp.

The provision would ban sale of Toshiba products in this country because of the illegal sale by a Toshiba subsidiary of computerized milling machines to the Soviet Union, allowing Moscow to make its submarines quiet enough to escape U.S. detection.

Rostenkowski indicated that the full, 199-member conference may meet next week and said work should begin in earnest by Sept. 28 at the latest.

He has been pressing other committee chairmen to try to complete their work next month so Congress can have a bill on President Reagan's desk by Thanksgiving.

The conference will have to tread a narrow line between meeting the congressional objective of passing a tough trade bill that hits unfair trade practices and being labeled protectionist by the White House, thereby drawing a veto.

Reagan has threatened to veto the bill if substantial changes are not made in the versions passed by overwhelming bipartisan majorities in both the House and Senate.