It is an important problem that people can drive with the comfortable posture while they maintain optimum vision field. For the design of dump truck cab, the traditional design is ‘bottom-up’, which based on the H point. However, ‘Design by H-point’ can not meet the requirement of posture and vision field at the same time, people would always adjust their driving posture to achieve the needs of vision. A method of ‘design by eye-point’ was proposed to satisfy comfortable seating posture and vision field, in which the eye point was taken as a reference point instead of the H point. An experiment on the dump truck cab was designed to collect sitting posture photos of 55 participants. According to these statistical data, the optimum eye point can be located, and the distribution types of human joint points were given. The mathematical expressions were derived to describe the relationships between human joint points and eye point. The positions of seat and other control devices in the cab can be located on the basis of optimum vision field and comfortable driving posture. This approach can also be applied in the design of other engineering vehicle's cab.