Abstarct: Helicopter-borne electromagnetic (HEM) frequency-domain surveys are used as a fast and high resolution exploration method for mapping the resistivity of the earth’s subsurface. There are several methods for interpreting and modeling of HEM data. These methods are classified into two general groups: (1) direct transform of data to a generalized model such as a half-space, and (2) inversion of data to a specific model such as a laxyered earth, where a starting model is used, followed by iterative fitting of the data in the least-squares sense. The first group methods have high speed but low precision of model parameters. In contrast, iterative inversion methods have high speed of computation and in addition produce high accurate results, but its final model response is dependent to the correct selection of the starting model. One of the most used methods of the second class is the laxyered earth inversion using the Levenberg-Marquardt (LM) technique baxsed on singular value decomposition (SVD). The main purpose of this study is providing a suitable algorithm to develop a reliable software for applying this method on inversion of frequency-domain HEM data to obtain high resolution resistivity images and also acquire the thickness of the earth’s laxyers. To achieve the goal it is firstly attempt to provide an efficient algorithm to write a reliable forward modeling and partial derivatives computation codes within the MATLAB software. In the next step, the required Levenberg-Marquardt inversion codes baxsed on the SVD method have been developed. The obtained results of forward modeling and partial derivative computation of synthetic models using the written program and comparing them with the results of a commercial program indicate the modeling computation of this new developed program is precise enough. In addition, the inversion routine has been tested on noise-free and noise-contaminated synthetic data of laxyered models and it has been observed that the estimated model is very close to the true model in each case. This program has also been used to invert a set of synthetic data of a 3-D model to further evaluation. The obtained results indicate the final resolved model is in a great accordance with the true 3-D model. Once the accuracy of the developed inversion program has been attained confidently, a set of real HEM data, of south Damghan area in Semnan province, has finally been inverted with this program and its results have been compared with those obtained with direct transformation methods. The results show that the produced data of the estimated model using the developed program fit better than the data of direct transformation methods to the field data.