With the aim to preclude the effect of penetration friction component (PFC) between the penetration shaft and surrounding material during a penetration process, an improved cone penetrometer with a mini force transducer embedded in the cone tip was developed. This kind of cone penetrometer could measure the density of soil and silage correctly. The results showed that the effect of PFC could be negligible in the two kinds of soil samples. But during the density measurement of the two different density chopped maize samples, PFC accounted for 32.56% and 34.05% respectively in the measurement value of force sensor. When there was no resistance on the cone, the measurement value of embedded force sensor was zero, whereas the measurement value of force sensor were about 110N and 280N. Appreciable error was found in the original test results for chopped maize.