Exhibit 5.1

Campbells LLP Floor 4, Willow House | Cricket Square Grand Cayman KY1-9010 | Cayman Islands @campbellslegal.com t. +1 345 949 2648 | f. +1 345 949 8613 campbellslegal.com   Our Ref: ACL 00773-42139 Your Ref:

Leishen Energy Holding Co., Ltd.

8 June 2026

Dear Sirs

Leishen Energy Holding Co., Ltd.

We have acted as Cayman Islands counsel to Leishen Energy Holding Co., Ltd. (the “Company”) in connection with the Company’s registration statement on Form F-3 including all amendments or supplements thereto (the “Registration Statement”), filed with the United States Securities and Exchange Commission (the “Commission”) under the U.S. Securities Act of 1933, as amended (the “Act”). The Registration Statement relates to the offering, issuance and sale from time to time, in one or more offerings, of up to US$150,000,000 of the following securities of the Company (the “Securities”):

(i) class A ordinary shares of a par value of US$0.001 each of the Company (the “Class A Shares”);

(ii) warrants to purchase the Class A Shares (the “Warrants”) issuable pursuant to the terms of a warrant agreement and a warrant certificate (together, the “Warrants Documents”);

(iii) debt securities of the Company which may be convertible into the Class A Shares (together, the “Debt Securities”), each series of the Debt Securities to be issued pursuant to a debt securities document or agreement to be entered into by the Company (each, a “Debt Securities Agreement”), which Debt Securities are not subject to the Trust Indenture Act of 1939 and accordingly will not be issued under an indenture with a trustee;

(iv) rights to purchase the Class A Shares (the “Rights”) issuable pursuant to the terms of a rights agent agreement and a right certificate (together, the “Rights Documents”); and

(v) units composed of any combination of the securities described above (the “Units”) issuable pursuant to the terms of a unit agreement and a unit certificate (together, the “Units Documents”).

We are furnishing this opinion as Exhibit 5.1, 8.1 and 23.2 to the Registration Statement.

For the purposes of this opinion, we have reviewed only originals, copies or final drafts or conformed copies of the following documents:

The following opinions are given only as to, and based on, circumstances and matters of fact existing and known to us on the date of this opinion letter. These opinions only relate to the laws of the Cayman Islands which are in force on the date of this opinion letter. In giving these opinions we have relied (without further verification) upon the completeness and accuracy of the documents set out above. We have also relied upon the following assumptions, which we have not independently verified:

Based upon the foregoing and subject to the qualifications set out below and having regard to such legal considerations as we deem relevant, we are of the opinion that:

shall be validly issued, fully paid and non-assessable.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the reference to our firm under the heading “Legal Matters” and elsewhere in the prospectus included in the Registration Statement. In giving such consent, we do not thereby admit that we come within the category of persons whose consent is required under Section 7 of the Act or the Rules and Regulations of the Commission thereunder.

Yours faithfully

/s/ Campbells LLP

Campbells LLP