After researching the origins of those ethical problems,the paper puts forward corresponding ethical principles to direct the ethical practice of genetically-modified crops,so as to ensure the research and application of these crops will be developed favorably for human beings and ecology environment.

From the viewpoint of ethics, it is the rational response of ethical practice and the distillation of the ethical theory.

But utilitarianists has expounded and developed its doctrine in controversies, especially has recently advanced many new arguments in practical ethics, such as abortion, euthanasia and environmenta.

Engineering ethics are both a kind of professional ethics and practical ethics.

In con-trast, the new concept of practice not only entails natural protection and perfection, but also implies a promotionof ecological practice to its essential form.

Objective value relations exist between humans and nature in ecological practice, human needs is the balanced judgment of these relations.